Suu Tam Xay Dung Va Su Dung He Thong Bt Hoa Hoc de Hinh Thanh Va Phat Trien Khai Niem Axit Bazo Trong Chuong Trinh Hoa Hoc Vo Co Thpt Nang Cao 5324

7/31/2019 Suu Tam Xay Dung Va Su Dung He Thong Bt Hoa Hoc de Hinh Thanh Va Phat Trien Khai Niem Axit Bazo Trong Chu

1/171

LUN VN TT NGHIP

Su tm, xy dng v s dng h

thng bi tp ha hc hnh thnh vpht trin khi nim axit baz trong

ch ng trnh ha hc v ctrung hcph thng (nng cao)


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PHN I: M U

1. L do chn ti

i mi gio dc l mt trong nhng nhim v quan trng ca ngnh

gio dc o to trong giai on hin nay. i mi ni dung, phng php

dy hc c hiu qu cao cn trang b cho hc sinh h thng kin thc c bn

vng chc.Trn c s hc sinh bit vn dng sng to kin thc gii quyt

cc vn hc tp v thc tin cuc sng.

Mc tiu ca nh trng ph thng l trang b kin thc ph thng c

bn tng i hon chnh gip hc sinh nm vng hiu bit khoa hc. Mn

ha hc gp mt phn quan trng trong mc tiu o to trng ph thng.

Chng trnh ha hc ph thng bao gm cc khi nim ho hc c bn ban

u v dn pht trin nhng khi nim , vic ging dy ha hc ph thng

phi ch n nhiu khi nim, axit baz l mt trong nhng khi nim c

bn, c tm quan trng i vi khoa hc ha hc. hiu v truyn th y ni dung v s hnh thnh v pht trin khi nim axit baz. Gio vin

cn nm vng qu trnh hnh thnh pht trin khi nim ny m bo vic

ging dy c hiu qu p ng nhu cu gio dc.

Trong chng trnh ph thng khi nim axit baz c cp rt

sm ngay t phn m u v ha hc lp 8 v c cng c cc lp v cp

hc tip theo. Khi nim axit baz trong chngtrnh ph thng c hnh

thnh v pht trin qua nhiu giai on, l mt trong nhng ti c tm quan

trng c bit.

Axitbaz l cc hp cht quan trng v ph bin, c nhiu ng dng

trong i sng, trong sn xut v nghin cu khoa hc.

Cc phn ng xy ra trong dung dch thng lin quan n khi nim

axitbaz.


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2

Khi nim axit baz v phn ng axit baz cho php h thng ha

cc hp cht ha hc, phn loi cc phn ng cc cht, gii thch cc hin

tng ha hc, chn tc nhn phn ng, cht xc tc

Sn phm tng tc axit baz hoc axit hay baz vi hp cht khc

u c ngha v mt thc tin. Nhiu phn ng ha hc v thc cht cng l

phn ng axit baz .

Vic hnh thnh khi nim axit baz ph thng t hiu qu cao khi

ngi gio vin nm vng ni dung v h thng qu trnh hnh thnh v pht

trin khi nim trong ton b chng trnh ph thng. ng thi gio vins dng phng php dy hc c hiu qu, ging dy c k hoch v lu ti

c im ca tng giai on c mt h thng bi tp c bn a dng phong

ph theo cc mc nhn thc khc nhau trong qu trnh hnh thnh v pht

trin khi nim axit baz.

Vi nhng l do trn, ti chn ti: Su tm, xy dng v s dng

h thng bi tp ha hc hnh thnh v pht trin khi nim axit baztrong chng trnh ha hc v ctrung hc ph thng(nng cao)

2. Khch th nghin cu

Qu trnh dy hc ha hc trng THPT

3. i tng v phm vi nghin cu

H thng bi tp ha hc hnh thnh v pht trin khi nim axit baz

trong chng trnh ha hc v c THPT (nng cao).4. Mc ch v nhim v nghin cu

a. Mc ch nghin cu:

Nghin cu la chn xy dng h thng bi tp ha hc v phng

php s dng chng trong vic hnh thnh v pht trin khi nim axitbaz

trong chng trnh ha hc v c THPT (nng cao).


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b. Nhim v nghin cu.

-Nghin cu c s l lun v qu trnh hnh thnh khi nim ha hc

v ngha tc dng ca bi tp ha hc trong vic hnh thnh khi nim ha

hc cho hc sinh bc THPT.

- Phn tch chng trnh sch gio khoa phn ha hc v c bc THPT

xc nh ni dung v dung lng khi nim axit baz .

- La chn, xy dng h thng bi tp ha hc v axit baz trong

chng trnh ha hc v c THPT chng trnh nng cao.

- Nghin cu phng php s dng h thng bi tp trn hnh thnh

khi nim axit baz.

- Thc nghim s phm xc nh tnh ph hp ca h thng bi tp

trn v kim nghim tnh hiu qu ca cc xut.

6. Phng php nghin cu

S dng phi hp cc phng php sau:

-Nhm cc phng php nghin cu l lun.-Nhm cc phng php nghin cu thc tin.

- Phng php hi tho chuyn , trao i kinh nghim.

- Phng php thc nghim s phm v x l thng tin.

7. Gi thuyt khoa hc

Trong dy hc ha hc nu gio vin xc nh ng ni hm v ngoi

din ca khi nim ng thi la chn xy dng c 1 h thng bi tp hahc a dng phong ph cc mc nhn thc khc nhau t s dng

chng 1 cch hp l v p dng nhng bin php rn luyn tch cc theo

hng dy hc tch cc, chng ta c th pht huy c t cht, nng lc sng

to, kh nng t duy ca hc sinh. T nng cao hiu qu ca vic dy hc.


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8. ng gp mi ca ti

- Phn tch qu trnh hnh thnh v pht trin khi nim axit baz

trong chng trnh ha hc ph thng.

- Xy dng v su tm: H thng cc bi tp c bn, nng cao nhm

hnh thnh khi nim axit baz trong chng trnh ha hc v c trung hc

ph thng (nng cao).

- xut phng php s dng h thng bi tp trong vic hnh thnh

khi nim axit baz trong chng trnh ha hc ph thng.


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PHN II: NI DUNG

Chng 1:C S L LUNV THC TIN CA TI

1.1. Nhng c s phng php lun ca s hnh thnh khi nim

ha hc

1.1.1. nh ngha khi nim [27]

Khi nim l hnh thc phn nh s vt v hin tng t cc mt ca

cc du hiu v cc mi quan h ch yu ca chng. Ni dung ca khi nimc m t bng li, bng cc k hiu ca ngnh khoa hc. Lnin nhn xt:

khi nim- sn phm cao nht ca tr tu, sn phm cao nht ca vt cht.

Trong l thuyt nhn thc, khi nim c xem xt nh l mt trong cc hnh

thc phn ng mt mc t duy tru tng.

Trong dy hc ho hc, khi nim l dng khi qut ho ca kin thc

v hnh thc t duy ca hc sinh trong qu trnh nm vng kin thc. S hnhthnh khi nim l mt trong cc vn trung tm quan trng ca qu trnh

dy hc ho hc. S hnh thnh khi nim chnh l qu trnh nhn thc c s

dng cc thao tc t duy khcnhau nhn thc cc du hiu, cc mi quan

h ca khi nim. S s dng cc khi nim trong qu trnh nhn thc chnh

l qu trnh hc cch t duy, thc hin qu trnh tm kim sng to. V vy n

kch thch s pht trin tr thng minh ca hc sinh.

1.1.2. Cutrc ca khi nim [27]

Khi nim bao gm hai mt dung lng v ni dung, chng c mi lin

h cht ch vi nhau.

Dung lng ca khi nim (ngoi din) c c trng bng s i

tng c khi qut trong khi nim. Dung lng phn nh mt s lng

ca qu trnh nhn thc.


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V d: Dung lng ca khi nim axit THCS l tt c cc cht c

cha nguyn t H kt hp vi gc axit, THPT bao gm cc cht c kh

nng nhng Hcho cc cht khc, c th xy ra trong cc dung mi, cng c

th l dung mi nc hoc cc dung mi khc nc, c th xy ra gia cc

cht ho hc trong cc phn ng ho hc,

Ni dung ca khi nim (ni hm) l s tng hp cc du hiu c

bn, du hiu bn cht chnh ca khi nim, ni dung chnh ca khi nim

phn nh mt cht lng ca kin thc th hin mc su rng ca khi

nim trong nhn thc. Ni dung ca khi nim axit THCS l c mt nguyn

t H lin kt vi gc axit; baz l cht c nhm hiroxyl lin kt vi nguyn

t kim loi v phn ng axit-baz l phn ng gia axit v baz.

Ni dung ca khi nim axit THPT l nhng cht c kh nng

nhng ion H cho baz , cn phn ng axit-baz l phn ng c s trao i

H gia cc cht phn ng.

Dung lng v ni dung l c tnh logic ca khi nim. Khi pht trin

mt khi nim th dung lng ca n c m rng v ni dung ca n c

o su, cc mi lin h ca n vi cc khi nim khc c thay i, m

rng v pht trin ln. Nh vy cu trc ca khi nim nh l h thng cc

du hiu c bn m c m ra qua ni dung khi nim.

1.1.3. C s phng php lun hnh thnh khi nim ho hc [27]

Th gii vt cht xung quanh chng ta l ngun gc to ra cc khinim. S hnh thnh khi nim l mt qu trnh nhn thc phc tp, c da

trn logic ca s nhn thc khoa hc v s chuyn bin khch quan t khng

bit n hiu bit trong nhn thc ca con ngi.

Phng php lun ca qu trnh hnh thnh khi nim l hc thuyt

nhn thc ca Lnin: T trc quan sinh ng n t duy tru tng v t


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n thc tin l con ng bin chng ca s nhn thc chn l, nhn thc

thc tin khch quan. Nhng iu thu nhn c t trc quan sinh ng

(cm gic, tri gic biu tng) l im xut phtban u ca vic dyv hc

cc khi nim ho hc.

Con ng nhn thc, hnh thnh khi nim c m t bng s

sau:

S vn ng ca nhn thc t cm gic n t duy tru tng l s

vn ng ng thi ca kin thc t hin tng n bn cht. S chuyn i

ca t duy (cm gic n tru tng) trong qu trnh hnh thnh khi nimv s vn dng khi nim o su, m rng kh nng nhn thc v dung

lng v ni dung trong nhn thc ca cc c th. V vy trong qu trnh

hnh thnh khi nim cn xc lp mi lin h cht ch ca khi nim vi

biu tng, s tru tng l thuyt vi thc nghim v nhng kt lun v ni

dung ca khi nim phi c hnh thnh trong hot ng thc tin, vn

dng khi nim.Trong dy hc, s hnh thnh khi nim c th i theo mi lin h h

thng ca qu trnh nhn thc ni chung: T trc quan sinh ng cm gic

s phn nh tri gic biu tngkhi nim.

Qu trnh hnh thnh khi nim bng s t duy l thuyt c rt

ngn bc nghin cu thc nghim v tng cng mc l thuyt, thay s

Trc quan

Cm gic

Tri gic

Biut n

Khi nim(nhngha)

Hnhthnh

T duy tru t ng

Khiqut

Vndng

Thc tin


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quan st thc tin (th nghim ho hc) bng m hnh, phng tin k thut v

s dng rng ri phng php nu vn , xut gi thuyt, suy din -din

dch, m hnh ho thc hin cc bc i khi qut ho l thuyt. Qu trnh

ny khng lm gim vai tr thc nghim ho hc, hoc cc s kin, kinh

nghim c ca hc sinh hay php qui np trong dy hc.

V vy tu theo ni dung khi nim, logic bn trong ca n m gio

vin c th chn cc con ng hnh thnh khi nim t trc quan hay t t

duy l thuyt khi hnh thnh biu tng khi qut hnh thnh khi nim.

1.1.4. Nguyn tc hnh thnh khi nim ho hc trng phthng [27]

Trn c s l lun dy hc v tm l dy hc cng vi tnh cht c th

v quy lut ca s nhn thc ho hc m s hnh thnh cc khi nim ho hc

trong dy hc ho hc ph thng cn m bo cc nguyn tc sau:

1. S hnh thnh khi nim ho hc cn i t cc v d v i tng,

hin tng ho hc in hnh, phn tch, xc nh ng ni dung cakhi nim.

2. Cn t khi nim nghin cu ban u trong s pht trin (theo dung

lng-ni dung) ca nv cc mi linhvi cc khi nim khc.m bo

tnh nh hng pht trin ca khi nim.

3. C s thng nht hp l cc mt cm gic trong ni dung ca khi nim,

php qui np v suy din trong hot ngt duy hnh thnh khi nim.4. Tng cng s dng cc k hiu, ngn ng ho hc nh l mt hnh

thc biu th khi nim v vn dng chng trong hc tp.

5. C s thng nht trong m t nh lng v nh tnh ca khi nim.

6. Cn ch n tnh thng nht ca nhng nt ring bit, c th v

chung nht trong khi nim v cc mi lin h qua li gia chng.


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7. S hnh thnh khi nim phi c thc hin trong cc hot ng

hc tp th hin cc mi quan h kin thc v k nng, kin thc v thc tin.

8. Tng cng kh nng vn dng ca cc khi nim c hnh

thnh qua hot ng hc tp ti u ho s pht trin t duy hc sinh.

Nh vy nhng con ng phng php lun ca s hnh thnh khi

nim ho hc c xc nh vi s cn nhc, tnh ton n cu trc ca khi

nim, tnh cht v vai tr ca n trong ton b h thng khi nim ho hc

ph thng.

1.2. Cc giai on quan trng ca s hnh thnh khi nim hohc [27].

Qu trnh hnh thnh khi nim ho hc trng ph thng bao gm

cc giai on: S hnh thnh khi nim, s pht trin khi nim v s lin kt

cc khi nim c lin quan trong ni dung ca n.

S la chn phng php hnh thnh cc khi nim c th cn cn c

vo c im ca khi nim, mc nhn thc ca khi nim (dung lng

ca khi nim), mc kin thc ca hc sinh, vai tr, ngha v tm quan

trng ca khi nim trong chng trnh ho hc ph thng.

1.2.1. S hnh thnh khi nim [27].

Trong qu trnh dy hc ho hc, h thng cc khi nim ho hc c

hnh thnh dn dn v pht trin trn c s cc hc thuyt ho hc khc nhau.

Thng qua cc qu trnh ny m dung lng v ni dung ca khi nim c

m rng, o su dn.

Hnh thnh khi nim ho hc c bn nht c thc hin ngay t cc

bi hc ho hc u tin THCS. Cc khi nim ho hc c bn c hnh

thnhbng hai con ng khi qut qui np t cc ti liu cm gic v con

ng kt lun suy din t cc qui lut, hc thuyt, nh lut bit lp

lun, khi qut thnh khi nim.


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i vi giai on u ca s dy hc ho hc (THCS) s hnh thnh

khi nim bng con ng khi qut qui np l c trng nht, c s ca n l

s khi qut ho t cc t liu thc nghim hnh thnh khi nim.

+ Khi qut quy np l phng php xy dng khi nim i t thc

nghim hay cc t liu nghin cu khi qut thnh khi nim (nh

ngha)Bc u, chn v d thc nghim, t liu hay s kn in hnh, em

phn tch, so snh tm ra cc du hiu chung ca khi nim. Trong cc du

hiu chung , xc nh du hiu bn cht, t rt ra nh ngha khi nim

v tin ti vn dng khi nim. Sau thit lp mi lin h gia khi nim c hnh thnh vi cc khi nim gn k. S hnh thnh khi nim bng con

ng khi qut qui np c thc hin theo mt logic xc nh bao gm cc

giai on:

1. Phn tch, so snh cc i tng in hnh lm r cc du hiu

chung ca khi nim.

2. La chn v lm chnh xc ho cc du hiu bn cht tc l tch duhiu bn cht khi cc du hiu khng bn cht.

3. Pht biu nh ngha v khi nim.

4. Thit lp cc mi lin h gia khi nim vi cc khi nim khc

v phn chia gii hn vi cc khi nim gn k.

5. Xc nh v tr ca khi nim trong s phn loi tng ng v vn

dng khi nim c hnh thnh.+ Suy din - din dch l phng php xy dng khi nim bng con

ng lp lun theo logic nhn thc. Phng php ny thng c dng

xy dng khi nim ho hc sau khi nghin cu ni dung l thuyt c bn.

Bc u cn chn tin cho s kt lun ca khi nim, tip theo a ra

nh ngha khi nim, phn tch nh ngha lm sng t cc du hiu bn

cht, sau thit lp mi lin h vi cc khi nim gn k v vn dng. S


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hnh thnh khi nim bng con ng suy din l thuyt c s dng hnh

thnh cc khi nim tru tng bng cch lp lun theo logic hnh thc xut

pht t cc hc thuyt, qui lut, nh lut m phn tch cc hin tng tm ra

nt bn cht ca khi nim. V d nh cc khi nim nguyn t, ng v, lin

kt ho hc, ho tr, obitan nguyn tCu trc ca logic hnh thnh khi

nim bng con ng suy din l thuyt bao gm:

1. S la chn tin xut pht cho kt lun ca khi nim.

2. Nu kt lun v nh ngha khi nim v lm chnh xc ho cc du

hiu bn cht ca n.3. Xc nh v tr ca khi nim trong h thng kin thc l thuyt v

milin h vi cc khi nim khc.

4. Chnh xc ho khi nim, phn bit vi cc khi nim gn k, m

rng khi nim trong cc tnh hung ring bit.

5. Vn dng khi nim vo vic gii cc bi tp nhn thc khc nhau.

Nh vy cc khi nim ho hc c th c hnh thnh bng cc con

ng nh:

* T th nghim ho hc cc qui luts m t nh tnh, nh

lngkhi qut nt bn cht khi nimvn dng.V d: Cc khi nim

phn ng ho hc, n mn in ho, nh hng ca nng , nhit , xc tc

n tc phn ng ho hc, s in li

* T s t duy l thuyt da trn cc hc thuyt phn tch cc hin

tng tm ra nt bn cht t hnh thnh khi nim.

V d: Cc khi nim lin kt ho hc, ho tr, s oxiho, s lai ho cc

obitan, phn ng oxiho kh.

* T s m t kinh nghim i n gii thch l thuyt v ni hm ca

khi nim


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V d: Phn tch cu trc phn t cc cht hu c qua m hnh gii

thch v tnh cht cc loi hp cht hu c, phn tch cu trc tinh th, cc

dng mng tinh th gii thch tnh cht cc cht c cu trc, dng mng tinh

th tng ng.

1.2.2. S pht trin khi nim [27]

Trong chng trnh ho hc ph thng, cc khi nim hnh thnh

giai on u nghin cu ho hc THCS c pht trin lin tc theo ba

con ng c bn l: S o su khi nim hay tng ni dung ca khi

nim. S o su bn cht ca khi nim bng cch m ra qui lut mi bntrong khi nim v thay i cc mi lin h bn trong gia cc thnh t ca

chnh bn trong khi nim.

Khi nim axit-baz THCS nghin cu phn t hp cht c cha

nguyn t H (axit) hay cha nhm nguyn t OH(baz).Khi nimny c

pht trin THPT bng cch o su bn cht ca khi nim l c s cho v

nhn proton v phn ng axit-baz lphnng c s trao i proton. Nhvy, ni dung ca khi nim tng ln vi c nhng cht khng c nguyn

t H cng c tnh axit (nh ion 2Cu ) hay vi nhng cht khng c nhm OH

cng c tnh baz (nh 3NH ). Cng vi khi nim axit-baz , khi nim

mui cng c mrng v pht trin hn THPT (mui l nhng cht),

v do dung dch mui c th c mi trng axit, baz hay trung tnh tu

thuc vo thnh phn cu to ca mui. Cc khi nim ho hc c bn khccng c pht trin bng con ng ny.

S m rng khi nim bng cch tng dung lng ca khi nim hay

cn gi l con ng m rng din. Cckhi nim c pht trin bng cch

khi qut cc i tng mi trong khi nim ny. Khi nim axit-baz c bn

cht l s cho nhn proton. Cc cht c th khng c du hiu l nguyn t H


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hay nhm nguyn t OH nhng vn th hin tnh cht axit hay baz . T s

m rng din ca khi nim m cn xc nhcc mi lin h mi gia khi

nim v s phn loi cc i tng. Vi cch m rng din m khi nim ho

hc c pht trin dn, cc khi nim cht, PHH c pht trin a dng

v ngy cng i su vo bncht ca chng.

1.2.3. S lin kt cc khi nim [27].

S pht trin khi nim c hon thin bi s lin kt ca cc khi

nim tc l s thng nht ca chng trong mt h thng kin thc trn c c

l thuyt xc nh. Trong dy hc ho hc s lin kt khi nim c thchin khi tng kt kin thc nhm thit lp mi lin h gia cc khi nim

c mt ci nhn khi qut v tng mng kin thc trong ton b chng trnh.

Nh l h thng kin thc theo cc khi nim ln: Kim loi, phi kim, lin kt

ho hc, cu to nguyn t,hirocacbon, hp cht c nhm chc

S lin kt cc khi nim c tin hnh bng s khi qut su l thuyt

trn c s l thuyt ch o vi s s dng rng ri mi lin h trong mn hcv lin mn hc.

S hnh thnh, pht trinkhi nim i hi s t chc hp l hot ng

ng b ca gio vin v hc sinh. Gio vin t chc cho hc sinh tm ti,

khm ph nhng du hiu bn cht ca khi nim, khi qut trong nhn xt,

nh ngha v vn dng trong cc tnh hung hc tp, thc tin c lin quan.

1.3. Khi nim axit-baz trong chng trnh HHPT.1.3.1. Khi nim axit baz trong chng trnh THCS (Thuyt

nguyn t, phn t)

1.3.1.1. Thuyt nguyn t, phn t

Sau khi c nghin cu v cht v s bin i ca cht, hc sinh tm

hiu v cu to ca cht bit r nguyn nhn s bin i . Nhng nguyn


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liu ban u cu to nn cc cht l nhng nguyn t ha hc, nguyn t ha

hc gm nhng ht v cng b nh gi l nguyn t.

Cc cht u c to nn t nhng ht v cng nh, trung ho v in

gi l nhuyn t. C hng chc triu cht khc nhau nhng ch c trn mt

trm loi nguyn t.

VD: Nguyn t Hiro : H - 1 nguyn t hiro

Cht c th do mt hoc nhiu nguyn t ha hc cu to nn. Mi n

cht hay hp cht u gm mt tp hp v cng nh (ht vi m) tham gia

trong phn ng ha hc th hin y tnh cht ha hc ca mt cht . Phn

t l ht i din cho cht, gm mt s nguyn t lin kt vi nhau v th

hin y tnh cht ho hc ca cht. Phn t c th b chia nh trong phn

ng ha hc.

VD: Nc tinh khit gm cc phn t H2O, trong cc phn ng ha hc

c th chia thnh H v O

Hp cht c to thnh t hai nguyn t tr ln. Phn t l ht vi mi din cho cht m nguyn t li l ht vi m i din cho nguyn t. Vy

phn t ca hp cht gm t hai nguyn t tr ln v l nhng nguyn t

khc loi. VD : HNO3: 1 nguyn t H, 1 nguyn t N v 3 nguyn t O

1.3.1.2. Khi nim axit baz trong chng trnh THCS:

Trong qu trnh tip thu kin thc, hc sinh dn dn tm hiu v thnh

phn ca cc hp cht, quen dn vi mt s hp cht v c: oxit, axit, baz,muitrong cc bi v oxi-s chy, hiro, nc. Mc d quen vi tn gi

axit baz nhng n khi tm hiu tnh cht ha hc ca nc, thnh phn

cc hp cht v c, hc sinh mi c tm hiu v thnh phn ca axit baz

VD: H2O ha hp vi mt s oxit kim loi to ra hp cht thuc loi baz

Na2O + H2O 2 NaOH ; CaO + H2O Ca(OH)2


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nhn bit cc dung dch l axit hay baz, da vo s bin i mu

ca giy qu tm. Dung dch baz i mu qu tm thnh xanh. Dung dch

axit i mu qu tm thnh .

Thnh phn ha hc ca axit: l hp cht m phn t gm mt gc axit

lin kt vi mt hay nhiu nguyn t hiro (H)

Axit clohiric : HCl gc axit Cl : Clorua lin kt mt nguyn t H

Axit sunfuric: H2SO4 gc axit =SO4: Sunfat lin kt hai nguyn t H

Thnh phn ha hc ca baz : l hp cht m phn t gm mt

nguyn t kim loi lin kt vi mt hay nhiu nhm OH (hiroxit)

Ba(OH)2: Kim loi Ba lin kt vi 2 nhm OH

NaOH : Kim loi Na lin kt vi 1 nhm OH

Sau khi bit khi qut v thnh phn ha hc ca axit baz ,hc

sinh tip tc tm hiu v nhng tnh cht ha hc v nhng quan h gia axit

baz v quan h gia axit, baz v nhng hp cht v c khc.nh ngha axit: L hp cht m phn t gm c mt hay nhiu nguyn

t H lin kt vi gc axit.

VD: 1 nguyn t H lin kt vi gc clorua: HCl

3 nguyn t H lin kt vi gc photphat: H3PO4

nh ngha axit cn c th da vo tnh cht ha hc ca chng. Axit l

hp cht m thnh phn c nguyn t H, nguyn t H ny c th thay th

bng nguyn t kim loi to thnh mui

VD: HCl : nguyn t hiro c th thay th bng kim loi (Fe, Al,

Zn,) trong phn ng th gia kim loi vi axit

Zn + 2 HCl ZnCl2 + H2 ; Fe + H2SO4 FeSO4 + H2


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nh ngha baz: L hp cht m phn t c mt nguyn t kim loi

lin kt vi mt hay nhiu nhm hiroxit (- OH)

Cng thc chung M(OH)y trong y l ha tr ca kim loi M

VD : Fe(OH)2, Cu(OH)2, Ca(OH)2,

nh ngha baz da vo tnh cht ha hc. Baz l hp cht c phn

ng trung ha vi axit, to thnh mui v nc. Phn ng axit baz to

thnh mui v nc gi l phn ng trung ha

NaOH + HCl NaCl + H2O ; 2NaOH + H2SO4 Na2SO4 + 2H2O

1.3.2 Thuyt axit bazca Areniuyt [12]

- Thuyt axit baz xut pht t thuyt in li ca Areniuyt cho rng,

axit l nhng cht khi ha tan trong nc th phn li cho cation hiro +H , cn

baz l nhng cht khi ha tan trong nc th phn li cho anion hiroxyl -OH

.Th d, HCl l axit, NaOH l baz

+ -

+ -

HCl H +Cl

NaOH Na +OH

- Phn ng trung ha l phn ng gia axit v baz, to ra mui v

nc (l cht in li yu). Th d : HCl + NaOH NaCl + H2O

- Phn ng thy phn ca mui l phn ng gia ion ca mui vi

nc, kt qu lm cn bng phn li ca nc thay i, dn n mi trng

ca dung dch thay i. Th d, s thy phn ca Na2CO3

Na2CO3 2Na+

+ 2-3CO

2-

3CO + 2H O -

3HCO +-OH

Thuyt ca Areniuyt l thuyt axit baz sm nht. N gii thch c

nhiu tnh cht v phn ng ca cc axit, baz trong dung dch nc. Tuy nhin

thuyt ny c nhiu hn ch. N ch p dng ng cho dung mi l nc,

khng p dng c cho tt c cc dung mi, ng thi n cha thy c vai


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tr quyt nh ca dung mi trong s phn li ca axit, baz.Mtkhc, thuyt

Areniuyt khng gii thch c cc phn ng to ra mui ging nh phn ng

trung ha m trong li khng c H+hoc -OH tham gia. Th d :

NH3(k) + HCl(k) NH4Cl

V vy cn nghin cu chi tit cc phn ng xy ra trong cc mi

trng khng nc, cng nh nhng trng hp khng c s tham gia ca

dung mi nhm b sung v khi qut cc lun im ca Areniuyt. Hin nhin

rng, bt k mt thuyt axit baz khi qut hn cng bao hm c cc lun

im ca Areniuyt v coi n nh mt trng hp ring.Hin nay c mt s thuyt axit baz tng qut hn. c p dng

rng ri nht l 3 thuyt: Thuyt cc h dung mi do hai nh bc hc ngi

M l Kei v Franklin cng b vo nm 1905. Thuyt proton c cng b

vo nm 1923 ng thi bi nh ha hc an Mch Bronstet v nh ha hc

ngi Anh Lauri. Thuyt electron cng c ngh vo nm 1923 do nh

ha hc M Liuyt. Mc d cc thuyt ny xut pht t nhng lun im khc

nhau nhng chng khng chng i li nhau m h tr cho nhau.

Vn t ra l t mt h c th v tin hnh tng tc mt iu

kin nht nh, ngi ta s s dng thuyt no trong cc thuyt nu ra

cho thch hp.

Sau y chng ta s xem xt mt s thuyt axit baz ni trn

1.3.3 Thuyt axit baz ca Bronstet v Lauri [12]

Bronstet v Lauri a ra thuyt axit baz tng qut hn vi nh

ngha axit, baz ch lin quan ti proton: Axit l cht c kh nng cho proton,

baz l cht c kh nng nhn proton. V vy, thuyt axit baz ca Bronstet

v Lauri cn c gi l thuyt proton.

Th d, trong nc, 3CH COOH l axit v n nhng proton cho nc, cn

phn t 2H O l baz v n nhn proton tr thnh+

3H O :


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3CH COOH + 2H O -

3CH COO ++

3H O (a)

Trong phn ng ca amoniac vi nc, 3NH l baz v n nhn proton

ca 2H O cn 2H O l axit v n nhng proton cho 3NH

2H O+ 3NH +

4NH +-OH (b)

Xt phn ng (a): Theo chiu thun, axit 3CH COOH nhng proton

tr thnh -3CH COO , baz 2H O nhn proton v tr thnh+

3H O . Theo chiu

nghch -3CH COO nhn proton t tr thnh 3CH COOH , cn+

3H O th

nhng proton cho-

3CH COO tr thnh2H O . Theo nh ngha ca

Bronstet -3CH COO l baz v+

3H O l axit.Ngi ta gi cp 3CH COOH -

-

3CH COO v cp+

3H O - 2H O l nhng cp axit baz lin hp.

Xt phn ng (b): Theo chiu thun, baz 3NH nhn proton tr

thnh +4NH , cn axit 2H O nhng proton tr thnh-OH . Theo chiu

nghch, +4NH nhng proton cho-OH tr thnh 2H O , cn

-OH nhn

proton t +4NH tr thnh 2H O . Theo nh ngha ca Bronstet+

4NH l axit

v -OH l baz . Ngi ta gi cp +4NH - 3NH v cp 2H O --OH l nhng

cp axit baz lin hp.Nu k hiu cp th nht l A1- B1, cp th hai l A2-

B2, th hai phn ng axit baz trn u c vit nh sau:

A1 + B2 B1 + A2

Axit 1 Baz2 Baz1 Axit2

y l phng trnh tng qut ca phn ng axit baz theo Bronstet.

phn ng nyc s chuyn proton t axit 1 cho baz 2 v t axit 2 cho

baz 1.Nh vy s chuyn proton l bn cht ca phn ng axit baz theo

Bronstet.

Cc phn ng axit baz khc cng xy ra s chuyn proton theo

phng trnh tng qut nu trn:


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Axit 1 + Bz 2 Baz 1 + Axit 2

HCN + 2H O -CN + +3H O (c)

+

4NH +2-

3CO 3NH +-

3HCO (d)

-

2 4H PO + 2H O 2-

4HPO ++

3H O (e)

Nh vy tt c cc phn ng axit baz u bao gm hai cp axit baz

lin hp nm trong mt cn bng. Mt axit khng th hnh thnh baz lin hp

ca n nu khng c mt baz khc. Ngc li, mt baz cng khng th hnh

thnh axit lin hp vi n nu khng c mt axit khc. i vi mt cp axit

baz lin hp: axit cng d cho proton(lc axit cng mnh) th baz lin hpca n cng kh nhn proton (lc baz cng yu)v ngc li.

Cc v d trn chnh l nhng phn ng ion thu gn biu din bn cht ca

nhiu phn ng axit baz c th khc nhau.

Bng 1.1: mnh tng i ca cc cp axit baz lin hp

Axit Baz lin hp

Axit pecloricHClO

4

4ClO

Ion pecloratAxit bromhiric HBr Br Ion bromuaAxit nitric HNO3 3NO

Ion nitrat

Ion hiroxyl -OH H2O NcAxit triclo axetic Cl3CCOOH Cl3CCOO

-Ion tricloaxetat

Ion hirosunfat 4HSO

2

4SO Ion sunfat

Axit photphoricH3PO4

2 4H PO Ion ihir

phtphat

Axit nitrHNO2

2NO

Ion nitritAxit flohiric HF F- Ion floruaAxit formic HCOOH HCOO

-Ion format

Axit axetic CH3COOH CH3COO-

Ion axetat

Axit cacbonic CO2 + H2O 3HCO Ion hirocacbonat

Axit sunfuhiric H2S HS- Ion hiro sunfua

Ion amoni+

4NH NH3 Amoniac

Axit xianhiric HCN CN- Ion xianuaIon hiro sunfua HS- 2-S Ion sunfua

Mnh

Yu

Yu

Rtyu

Mnh

Rty

u

Lc

axittng

Lc

baz

tng


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Nc H2O -OH Ion hiroxylRu etylic C2H5OH C2H5O

-Ion etylat

Amoniac NH3 2NH

Ion amitHiro H2 H

- Ion hirua

Metan CH4 3CH Anion metyl

Bng 1.1. Sp xp cc cp axit baz lin hp theo mnh yu tng

i gia chng. Theo trt t t trn xung di, lc axit gim dn v lc baz

ca cc baz lin hp tng dn. Cc axit t +3H O tr ln l cc axit mnh.

Cc baz t -OH tr xung l cc baz mnh. V th, s dng bng 1.1 ta c

th xt on c chiu hng ca phn ng axit baz.V d : Hy cho bit hin tng xy ra khi nh dung dch 2Na S vo

dung dch HCl . Theo bng 1.1 axit HCl mnh hn axit 2H S v-HS rt

nhiu, do cc phn ng sau hu nh xy ra hon ton nn c kh hidro

sunfua thot ra:

HCl + 2-S -HS + -Cl

HCl + -HS 2H S +-Cl

Cc axit BronstetLauri u cha proton, v vy, chng cn c gi

l axit protonic. Cc axit protonic c th l phn t trung ha nh HCl ,

2 4H SO , 3 4H PO ,l anion nh-

4HSO ,-

2 4H PO ,-HS ,l cation nh +3H O ,

+

4NH ,3+

2 6[Fe(H O) ] ,Cn cc baz Bronstet-Lauri c th l phn t trung

ha nh 3NH , 2R-NH , 2R CO (R l gc hu c hoc halogen), piriin,

2H Ol anion nh2-

4HPO ,-OH , -Cl , -2NH , cc cation nh

+

2 3H N- NH ,

3+

3 5[Pt(NH ) (OH)] ,2+

2 5[Fe(H O) (OH)] ,

Thuyt Proton gii thch c tnh cht baz ca cc hp cht hu c

nh amin, ete, xeton v thioeteNh c cc cp electron t do, khi kt hp

proton, cc hp cht ny to thnh cc cation oni. Nhng ion ny l axit lin

hp ca cc hp cht .Di y ch ra cc phng trnh kt hp proton vo

cc nhm chc ca cc hp cht hu c trn:


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N: N H

+

+ H+

O:.. + H

+ O-H..

Nh trn bit, cc dung mi c chia thnh dung mi proton v

dung mi khng proton. Cc dung mi proton khng nhng c kh nng cho

proton m cn c th kt hp vi proton. Th d, vi t cch l dung mi, axit

axetic khan tng tc vi c 3NH v HCl :

3CH COOH + 3NH -

3CH COO ++

4NH

3CH COOH + HCl +

3 2CH COOH +-Cl

Phn ng th nht xy ra hon ton, phn ng th hai xy ra l thunnghch.

Cng nh axit axetic khan, cc dung mi proton khc, chng hn, nh

nc, amoniac lng u c coi l dung mi lng tnh. Bi v chng u c

kh nng kt hp vi proton v kh nng cho proton (ccphn ng t (a) n

(l) trn)

Cc dung mi khng proton l cc dung mi trung tnh (nh benzen,

toluen, tetraclorua cacbon, icloetan). Kh nng kt hp hoc cho proton

ca chng rt yu.

Thuyt proton tng qut hn thuyt axit baz ca Areniuyt. Cc axit

Bronstet rt a dng, khng ch bao gm nhng cht phn li trong nc thnh

proton m c nhng cht khng phn li trong nc thnh proton nh H2

,


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4CH Cc hiroxit kim nh NaOH, KOH,theo Areniuyt l baz, nhng

theo Bronstet Lauri th ch c -OH trong l baz, hn na, khng phi

ch c -OH m tt c nhng cht c kh nng nhn proton u l baz. Mt

khc, thuyt axit baz ca Areniuyt ch p dng cho dung mi nc, cn

theo thuyt Brosntet-Lauri c th p dng cho bt k dung mi no: H2O, NH3

lng, HF lng hay 3CH COOH khanv k c khi khng c dung mi nh:

3NH (k) + HCl (k) NH4Cl(r)

Tuy vy, thuyt proton ch gii hn cho nhng phn ng axit baz

trong c s trao i proton. C nhiu qu trnh tng tc, trong cc cht

th hin tnh axit v tnh cht baz, nhng theo thuyt proton khng cho l

phn ng axit baz, bi v khng c s trao i proton. Chng hn,

phn ng ca oxit kim loi v oxit phi kim to ra mui.

VD : CaO + SO3 CaSO4

Hoc phn ng gia SOCl2 v K2CO3 trong SO2lng :

SOCl2 + K2CO3 2KCl + 2SO2

u im ni bt nht l thuyt proton cho php nh gi nh lng lc axit

baz ca cc cht .

1.3.4 Tch s Ion ca nc [12].

Phn t nc va c th cho proton va c th nhn proton. Hai qu

trnh c m t bi cn bng t ionha ca nc :

2H O + 2H O +

3H O + -OH

i vi cn bng ny ta c :+ -

3

2

H O OH

2

H O

a .aK =

a

Qu trnh t ion ha ca nc cck yu, 250 C, = 1,81 . 910 ,

ngha l c 555 triu phn t nc mi c 1 ion +3H O v 1 ion-OH . V th,


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0

20

40

60

80

100

120

0 10 20 30 40 50 60 70 80 90 100

hot ca cc ion chnh bng nng , cn nc coi l nc nguyn cht

nn hot chp nhn l 1. Ta c :

K = [ +3H O ].[ -OH ] hoc vit gn l K = [+H ].[ -OH ]

K l hng s in li ca nc. N ph thuc vo nhit . Nh vy mt

nhit xc nh, tch nng ca ion +3H O vi nng ion-OH l mt

hng s. Hng s ny c gi l tch s ion ca nc, k hiu l2H O

K v c

trng nh lng cho s t phn li ca nc. Gi tr2H O

K c th tnh t 0G

ca phn ng in li ca nc 250

C nh sau :

2

0

H O

79,89.1000ln K 32,23

8,314.298

G

RT

=>2H O

K = 1,007. 1410 1. 1410

Nh vy, khi tng nng ion hiro trong dung dch th nng ion hiroxyl

s gim xung v ngc li, khi bit nng ca ion +3H O trong dung dch s

tnh c nng ca ion-

OH v ngc li.Qu trnh phn li ca nc l thu nhit : 2 2H O

+

3H O +-OH

Hoc n gin : 2H O +H + -OH 0298 58 /H kJ mol

V vy, theo nguyn l L Sa-t-li, nhit tng, qu trnh phn li ca nc

tng ln, ngha l tch s ion ca nc tng ln khi nhit tng xem hnh 1.1

v bng 1.2

Hnh 1.1: S ph thuc tch s ion ca nc vo nhit

KH2O


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toC

Bng 1.2: S ph thuc ca pH, tch s ion ca ncvo nhit

Nhit (0 C)2

14

H OK .10 pH ca mi trng

trung tnh0 0,11 7,48

10 0,29 7,27

20 0,68 7,08

25 1,0 7,0

30 1,46 6,92

50 5,47 6,63100 55,0 6,13

200 400 5,7

1.3.5. Hng s phn li axit v baz[12]

1.3.5.1. Lc axit.

a) Lc axit :Lc axit ( mnh yu ca axit) ca axit proton trong dung dch nc c

xc nh bi mc din bin ca cn bng sau :

HA + 2H O +

3H O +-A (1.1)

+ -

3

2

[H O ].[A ]K =

[H O].[HA](1.2)

V [H2O] thay i khng ng k nn c th gp vo hng s K thnh Ka:


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+ -

3a

[H O ].[A ]K =

HA(1.3)

hoc c th vit n gin l+ -

a[H ].[A ]K =

[HA] (1.4)

Ka c trng nh lng cho s phn li ca axit theo phng trnh 1.1.Ka

c gi l hng s axit. mt nhit nht nh, Kacng ln (axit phn li

cng nhiu) th axit cng mnh. Do , c th dng Ka c trng nh

lng cho mnh ca axit.

Cc axit mnh hn

+

3H O (xem bng 1.1) phn li hu nh hon tontrong nc. Chng hn, i vi axit clohiric :

HCl + 2H O +

3H O +-Cl

Trong dung dch ch tn ti cc ion -Cl , +3H O , khng c phn t HCl .

V vy, khng th xc nh c hng s axit ca axit clohiric.

Cc axit yu, thng phn ng rt t vi nc, trong dd nng ion+

3H O v-

A nh, nng HA ln nn Kanh. V vy, so snh lc axit cachng, ngoi vic s dng gi tr Ka, thun tin hn, ngi ta cn thng

dng gi tr pKa :-[A ]

pK = -lgK = pH- lga a [HA]

Ngc vi khi dng Ka, gi tr pKacng ln th axit cng yu.

i vi cc axit mnh, Ka 1, do pKa< 1 , tc pKac gi tr m.

Cc gi tr Ka

v pKai vi mt s axit yu c ch ra bng sau :

Bng 1.3: Cc gi tr Ka v pKai vi mt s axit yu 250 C

Axit Ka pKa Axit Ka pKa

-

4HSO 21,0.10 2,00

-

2 4H PO 6,31.810 7,20

3 4H PO 7,5.310 2,12

-

4NH 5,5.1010 9,30

HNO2 7,2.410 3,14 HCN

106,5.10 9,19


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HF 6,5. 410 3,192-

4HPO 1,26.1210 11,90

3CH COOH 4,75.510 4,757 -HS 3,00.

1310 12,50

CO2+H2O(H2CO3) 4,5.710 6,35

H2S 1,0.710 7,00

Da vo bng 1.3 ta thy, axit -4HSO mnh hn axit 3 4H PO v axit

3 4H PO li mnh hn axit HNO2i vi axit a chc, qu trnh phn li ca

mi nc s tng ng vi mt gi tr Kanht nh v1 2 na a aK > K > ... > K . VD

i vi axit 3 4H PO : 1 2 3a a aK > K > K . i vi cc axit yu c hai i lng

hng s axit Kav in li u c gi tr nh hn nhiu so vi 1. Tuy

nhin, chng c nhng im khc nhau c bn l: gi tr Kai vi mt axit

khng thay i theo nng , cn gi tr in li li ph thuc vo nng

ca dung dch.

VD: i vi axit axetic khi nng khi nng gim t 0,1 mol/lxung 0,01 mol/l th in li tng ln t 1,3 ln 4,3% :

Nng mol/l (%) [ +H ] pH

0,1 1,3 0,0013 2,88

0,01 4,3 0,0004 3,88

S d nh vy l v gim nng axit tc l tng nng nc lm

cho cn bng 1.1 chuyn dch v pha phn li thm (theo nguyn l L Sa-t-li) dn ti tng . Tuy vy, s pha long dung dch lm gim nng ion

+H trong dung dch t 0,0013 mol/l xung cn 0,0004 mol/l ngha l lm cho

dung dch km axit i (pH tng t 2,88 ln 3,88).

b) Xc nh hng s axit

Hng s axit c th c xc nh theo nhiu phng php khc nhau:


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Hng s Kac th tnh theo phng php lp chu trnh Booc Hab

da trn cc d kin nhit ng nh: nng lng ion ha, i lc electron, nhit

hirat ha, nhit ha tan, nng lng t do GipSau t phng trnh:

0 lnG RT K a

Ta xc nh c hng s axit Ka .

Hoc c th da vo in li ca axit xc nh c bng thc nghim

VD: 025 C, dung dch axit CH3COOH 0,01 M c in li =

4,3%. Hy tnh hng s axit Kaca axit axetic 025 C.

Theo h thc lin h gia hng s phn li Kav in li ta c:2 2

5C 0,01.(0,043)K = K = K =1,8.101- 1- 0,043a a a

1.3.5.2. Lc Baz[12].

a) Lc Baz.

Baz quen thuc nht l ion hiroxyl-OH n c to ra do sphn li ca

cc hiroxit kim loi, hoc do phn ng chim proton ca nc:

NaOH(r) 2H O +(aq)

Na +-

(aq)OH

NH3(aq)

+2

H O +4NH +-OH

-F +2

H O ( )

HFaq

+ -OH

Hiroxit ca cc kim loi kim th (tr Be) u l nhng baz mnh.

Trong NaOH, KOH v 2Ca(OH) c dng ph bin nht. Cc baz mnh

phn li hon ton trong nc nn to ra dung dch cha ion hiroxyl vi nng

ln. Cc baz yu ch to ra cc ion hiroxyl nng nh. biu din

lc baz ( mnh yu ca baz) ngi ta s dng hng s baz bK .


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i vi cc hiroxit kim loi:

M(OH)nn+M + -nOH

bK =n+ - n

n

[M ][OH ]

[M(OH) ](1.5)

i vi cc baz nhn proton t nc (k hiu l B), ta c:

B(aq) + H2O+BH

+ -OH (1.6)

bK =+ -

[ ] [ ]

[ ]

BH OH

B

(1.7)

Hm s baz bK thng nh nn thun tin ngi ta thng dng i

lng bpK

bpK =- lg bK = lgb

1

K ( 1.8)

mt nhit lng nht nh, gi tr bK cng ln (p bK cng nh) th baz

cng mnh,bK cng nh (p

bK cng ln) th baz cng yu. Bng 1.4 chobit gi tr bK v p bK camt s baz thng gp. Ion

-OH phn ng vi

nc to ra nc v chnh n:-OH + H2O

-OH + H2O

Nu nh p dng biu thc (1.6) (ion -OH ng vai tr baz B) th ta c

bK ca-OH bng 1.

Bng 1.4: Hng s bazbK v p

bK i vi mt s baz yu 25o

C.Baz bK P bK baz bK P bK

-OH 1 0 3NH 1,8.510 4,7

2-S 7,7. 210 1,1 6 5 2C H NH 4,2.1010 9,38

2 5 3(C H O) N 5,2.410 3,28 CH3COO

-5,7. 1010 9,24


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2-

3CO 2,4.410 3,62 -F 1,5.

1110 10,82

3 3)(CH N 6,3.510 4,20

-

3NO 4,0.11610 15,4

C N

1,39. 510 4,70 -Cl 3. 2310 22,5

Bng 1.4 cho thy anion ca cc axit yu nh 2H S , HCN, 2 3H CO l cc

baz tng i mnh, cn cc anion ca cc axit mnh nh 3HNO , HCl l

cc baz rt yu. Bng 1.1 thy NH3, -F v cc baz ng trn -OH u l cc

baz yu hn-OH (k hiu l B). V th trong qu trnh cnh tranh chim

proton, -OH lun thng chng, do cn bng sau lun lch v pha tri,

ngha l : B + H2O BH+

+ -OH .

Ngc li cc baz mnh nh -OH v cc cht ng di -OH trong

bng 1.1 l cc baz mnh, do , trong phn ng vi nc chng s chim

hon ton proton v to ra -OH t nc.

-OH + H2O H2O + -OH

2-NH + H2O(1) NH3(k) +

-OH

Tm li, axit no cho proton mnh hn H3O+

cn -OH cn cc baz no

nhn proton mnh hn -OH th l baz mnh.

1.3.6. Khi nim v pH, pK v cht ch th axit-baz :

1.3.6.1. Khi nim v pH v pK[12].

Cn bng gia cc ion +3H O v-OH khng ch tn ti trong nc

nguyn cht m cn trong tt c cc dung dch long ca cc cht trong nc.

V vy h thc: K= [ +3H O ].[-OH ] hoc vit gn l K=[ +H ] c th c trng

cho tnh axit v tnh baz ca cc mi trng khc nhau.


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Bi v2H O

K 0, nn khng c mt dung dch nc no m , nng

ca ion +H hoc ca ion -OHbng khng. V vy, trong bt k mt dung

dch nc no cng lun tn ti ng thi cc ion +H v -OH .

i vi nc nguyn cht 2980K, ta c:

[ +H ].[ -OH ]=1,00.10-14

[ +H ]=[ -OH ]=10-7

mol/l

V vy, ngi ta c th dng nng ion +H v -OH nh gi mi

trng ca dung dch. nhit 298K, bt k dung dch nc no m

[ +H ]=[ -OH ]=10-7 mol/l u c gi l c mi trng trung tnh. Khi dung

dch c nng [ +H ] > 10-7 mol/l v [ -OH ] < 10-7mol/l th c gi l c

mi trng axit. Khi dung dch c [ +H ] < 10-7 v [ -OH ] > 10-7mol/l th c

gi l dung dch c mi trng baz .

biu th mc axit hay baz ca mi trng thay cho nng ion+H , ngi ta dng mt i lng khc tin hn, l ch s hiro k hiu l

pH v c nh ngha nh sau:

pH=-lg[ +H ]=lg+

1

H

Tng t nh vy, ngi ta nh ngha ch s hiroxyl pOH v pK nh sau:

pOH=-lg[ -OH ]=lg-

1

OH

pK=-lgK=lg1

K

v trong dung dch nc [ +H ].[ -OH ]=2H O

K nn ta c:

pH + pOH = p2H O

K

298K, pH + pOH = p2H O

K = 14

Mi trng s l trung tnh khi pH = 7 v pOH = 7

Mi trng s l axit khi pH < 7 v pOH > 7


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Mi trng s l baz khi pH > 7 v pOH < 7

Gi tr pH ca mi trng cng nh hn 7 th mi trng cng axit, pH cng

ln hn 7 th mi trng cng baz

Tch sion ca nc thay i theo nhit , v vy cc nhit khc nhit

phng, mi trng s l trung tnh khi pH ca dung dch ln hn hoc nh

hn 7.

1.3.6.2. Cht ch th axit-baz[12].

Chng trnh ho hc ph thng c cp n cc cht ch th ax it-

baz. l cc cht m khi i mu chng cho bit nng cc ion hiro(ch s hiro pH) trong dung dch. Mi cht ch th axit-baz ch bin i mu

trong mt khong pH nht nh, c trnh by bng sau:

Bng 1.5: Khongi mu ca mt s ch th axitbaz

Cht ch th Mu axitKhong pH

thay i muP

nIK Mu baz

Thylmolblue 1,2-2,8 1,7 VngMetyldacam 3,2-4,4 3,4 Vng

Bromophenol Vng 3,0-4,6 3,9 Xanh

Bromopresol green Vng 4,0-5,6 4,7 Xanh

Metyl 4,8-6,0 5,0 Vng

Bromothymolblue Vng 6,0-7,6 7,1 Xanh

Litmus 5,0-8,0 6,5 Xanh

Phenol Vng 6,6-8,0 7,9

Phenol phtalein Khng mu 8,2-10 9,4 Hng

Thymol Blue Vng 9,0-9,6 8,9 Xanh

Alizarin vng Vng 10,1-12,0 11,2

Alizarin 11,0-12,4 11,7 Tm

Ch thch:


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pnI

K l hng s axit-baz ca cht ch th, In l ch vit tt ca t

Indicator ngha l cht ch th

V d: Vitamin C l mt axit yu (axit ascorbic), mt khi lng mu

cht ny c xc nh bng cch chun vi dung dch NaOH. C th

dng metyl hay phenolphtalein lm cht ch th hay khng?

Tr li: Cht ch th l phenolphtalein

1.3.7. Dung dch m [12].

Dung dch im l dung dch c gi tr pH khng i khi pha long

hoc khi lm c hoc thay i rt t khi thm mt lng nh axit mnh haybaz mnh.

Cc dung dch m c thnh phn nh sau:

- Axit yu v mui ca n, chng hn nh dung dch ca CH3COOH v

NaCH3COO.

- Baz yu v mui ca n, chng hn nh dung dch ca NH 3 vNH4Cl.

- Mt mui trung tnh v mt mui axit, chng hn nh dung dch ca

Na2CO3 v NaHCO3.

- Hai mui axit c hng s axit khc nhau, chng hn nh dung dch

ca NaH2PO4 v Na2HPO4.

C hai cht trn vi nhau to thnh mt dung dch m c gi l mt

cp m.

1.3.7.1. Tnh pH ca dung dch m [12].

a) Dung dch m pha t axit yu v mui ca n.


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Th d: Tnh pH ca dung dch gm CH3COOH c nng ban u l

Ca (mol/l) v NaCH3COO c nng ban u l Cm (mol/l).

Trong dung dch, mui NaCH3COO phn li hon ton nn nng ban u

ca ion 3CH COO trong dung dch bng Cm (mol/l). Xt cn bng ca

CH3COOH v 3CH COO trong dung dch.

CH3COOH H+

+ 3CH COO

Nng ban u(mol/l) Ca H+

Cm

Bin thin nng (mol/l) -x +x +x

Nng cn bng Cax X Cm + x

V Kaca axit CH3COOH nh nn qu trnh phn li ca axit l yu nn

c th coi Cax Ca v Cm + x Cm.

Khi ta c th vit :+[H ].Cm

Ca= Ka Suy ra :

+[H ] = Ka .Ca

Cm

V pH = p Ka - lgCa + lgCm hay pH = p aK + lgCm

Ca (7.18)

y l biu thc tng qut tnh pH ca dung dch m pha t mt

axit yu v mui ca n.

b) Dung dch m pha t baz yu v mui ca n.

Th d: Tnh pH ca dung dch hn hp gm NH3c nng ban u

l Cb (mol/l) v NH4Cl c nng ban u l Cm (mol/l).

Trong dung dch mui NH4Cl phn li hon ton nn nng +

4NH bngCm (mol/l).

Tng t nh cn bng sau trong mt dd axit, ta tnh c:

Kb =[OH ].Cm

C

b

Suy ra : [OH ] = Kb .Cb

Cm


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pOH = pKb - lgCb

Cm

pH = 14pKb - lgCb

Cm

(1.10)

y l biu thc tng qut tnh pH ca dung dch m pha t baz

yu v mui ca n. T cc biu thc 1.9, 1.10 ta thy pH ca dung dch m

khng nhng ph thuc vo hng s axit yu hoc hng s baz ca baz yu

m cn ph thuc vo t l nng ca mui v axit hoc nng ca mi v

baz. Do , axit yu v mui ca n hoc baz yu v mui ca n ta c th

pha c cc dung dch m ca pH khc nhau bng cch thay i t l mui

v axit hoc mui v baz.1.3.7.2. Tc dng ca dung dch m [12].

- Dung dch m c kh nng gi cho pH ca n khng thay i khi b

pha long hay lm c hn khng nhiu. S d dung dch m c tc dng

l v khi b pha long hay lm c th nng ca mui v axit hay ca mui

v baz trong dung dch u lm gim hoc tng nh nhau nn t s ca cc

nng vn khng thay i lm cho pH ca dung dch khng thay i(xem cng thc tnh pH ca dung dch m 1.9 v 1.10).

- Dung dch m c kh nng gi cho pH ca dung dch thay i rt it

khi thm vo dung dch mt lng nh baz mnh hay axit mnh.

Bng 1.6 ch ra cc gi tr pH khi thm mt lng KOH hay mt

lng axit HCl vo dung dch m to bi axit CH3COOH 0,1M v

CH3COOK 0,1M.Bng 1.6: Gi tr ca pH ca dung dch m CH3COOH 0,1M v

CH3COOK 0,1M khi thm mt lng baz mnh hay axit mnh.

Lng

KOH

thm vo

[ +H ] (mol/l)

trong dung

dch m

pH ca

dung dch

m

lng HCl

thm vo

(mol/l)

[ +H ]

(mol/l)

trong dung

pH ca

dung dch

m


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(mol/l) dch m

0,0 1,75.10-5

4,757 0,0 1,75.10-5

7,57

0,0001 1,77.10-5

4,758 0,0001 1,75.10-5

4,756

0,001 1,72.10-5

7,766 0,001 1,79.10-5

4,748

0,005 1,58.10-5

4,801 0,005 1,93.10-5

4,713

0,010 1,43.10-5

4,844 0,010 2,14.10-5

4,670

0,050 0,583.10-5

5,234 0,050 5,25.10-5

4,280

Dung dch m c vai tr quan trng trong phng th nghim v trong

cng nghip ho hc. N c kh nng duy tr pH dung dch n nh thc hin

phn ng tng hp v c, tng hp hu c, c bit l cc phn ng ln men v

nhiu phn ng khc. Trong c th ca ng vt cao cp, c bit l ngi, pH

trong dch t bo, trong mu v trong nhng dch khc dao ng trong mt

khong rt hp l nh cc h m. Th d, pH ca mu ch thay i trong khong

7,307,42 (trung bnh 7,42) l do trong mu c cc h m sau:

- Axit cacbonic v mui bicacbonat MHCO3 (M =K, Na).

- Mononatri photphat NaH2PO4 v inatri photphat NaH2PO4.

- Hemoglobin v kali hemoglobinat.

- Axit hu c v mui ca axit hu c.

1.3.8. Phn ng axit-baz[12]

* S dung mi phn ca mui

Xt v mt hnh thc, phn ng trao i gia cc thnh phn ca mui

vi cc thnh phn ca dung mi c gi lphn ngdung mi phn. Trong

trng hp dung mi l nc th ngi ta gi lphn ng thu phn.

Th d:


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CH3COONa + H2O CH3COOH + NaOH (1.10)

Sau y s vn dng l thuyt v phn ng axit baz xem xt bn

cht ca phn ng dung mi phn.

1.3.8.1. S thu phn ca mui

Theo quan im ca thuyt Areniuyt th s thu phn l phn ng

ngc vi phn ng trung ho. Chng hn nh phn ng thu phn (1.10),

mui tc dng vi nc to thnh axit v baz.

Theo quan im ca thuyt Brestet, bn cht ca phn ng (1.10) cbiu hin phn ng ion thu gn ca n:

HOH + -3CH COO -OH + CH3COOH (1.11)

Phn ng (1.11) cng c dng ca phn ng axit baz kiu:

Axit 1 + Baz 2 Baz1 + Axit2

Tuy nhin, phn ng (1.11) c im khc bit l baz 1 ( -OH ) mnh

hn so vi baz2 ( -3CH COO ), tc l phn ng 1.11 xy ra ngc vi chiu

din bin bnh thng ca phn ng axit baz Brostet. Xt theo c hai quan

im th u thy s thy phn l phn ng ngc vi phn ng trung ho,

vy m n vn xy ra c. Nguyn nhn chnh l do yu t nng tc

ng ti cn bng cc phn ng .

Ta hy xt s thu phn ca 4 loi mui da vo axit hoc baz canhng ion hp thnh mui so vi nc. Xt nh th cho php tin on phn

ng thu phn ca mui to ra mi trng g.

a) Mui to thnh t baz mnh v axit mnh

Thuc loi ny c cc mui peclorat, clorat, nitrat, clorua, bromua,

ioua ca cc cation kim loi kim, kim ph (tr Be), h lantan v h actini.


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Th d: NaCl, MgBr2, La(NO3)3 , Ba(ClO4)2, Ac(CLO3)3.

Bi v cc ion gc axit cc mui ny u l cc baz yu hn nc (bng

1.1) nn chng khng phn ng vi nc theo kiu phn ng axit baz

Brostet, l ch phn ng to ra cc ion hirat ho theo kiu axit baz Liuyt

nh sau:

x+M + 2nH O 2 n[M(H O) ]x+

(cation hirat ho)

y-A + 2nH O y-

2 n[A(H O) ] (anion hirat ho)

V lc axit baz ca cc cation hirat ho v anion hirat ho loitrn u yu hn nc nn chng khng phn ng tip vi nc .

Nh vy, mui loi ny khng th thu phn, mi trng vn trung

tnh.

b) Mui to thnh baz mnh v axit yu:

Thuc loi ny c mui xianxua, axetat, cacbonat, sufua, photphat,fomiat ca cation kim loi kim, kim th (tr Be) h lantan, h actini.

Th d: KCN, Ba(CH3COO)2 , Na2S, Na3PO4, La(HCOO)3

Khi tan trong nc cc mui loi trn s phn li hon ton thnh cc

cation v cc anion. V cc cation ca cc mui u khng b thu phn

(mc a xt), cn cc anion u c lc baz mnh hn nc nn ch c cc

anion phn ng vi nc:

-A + 2H O HA +-OH

Baz1 Axit 2 Axit1 Baz


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Trong phn ng thu phn trn, anion -A ginh proton ca nc

to ra axit yu HA v gii phng ra bazmnh -OH lm cho dung dch c

mi trng baz.

Th d, xt phn ng thu phn mui K(HCOO) v Na3PO4

HCOO + 2H O HCOOH +-OH

3-

4PO + 2H O 2-

4HPO +-OH

2-

4HPO + H O

2

-2 4H PO +-OH

-

2 4H PO + 2H O 3 4H PO +-OH

Phn ng thu phn ion fomiat to ra axit fomic l axit yu v baz-OH lm cho dung dch c mi trng baz.

Phn ng thu phn ion photphat chi xy ra nc 1 v nc 2 l chnh,

cn nc 3 xy ra rt yu v ion -OH sinh ra nc 1 v nc 2 ngn cn s

to thnh axit photphoric nc 3. Dung dch c mi trng baz.

c) Mui to thnh t baz yu v axit mnh

in hnh ca loi mui ny l cc mui peclorat, clorat, nitrat, clorua,

bromua, ionua ca amoni v a s cc kim loi pha phi ca bng tun

hon. V nh: NH4Cl, Be Br2, AlCl3, Fe(ClO4)3, CrCl3

i vi loi mui ny ch c cc cation phn ng ng k vi nc:

4NH + 2H O NH3 + 3H O

x+M + 2 2H O (x-1)+M(OH) + 3H O

Thc ra qu trnh thu phn cation kim loi cacc mui ny xy ra nh sau:

x+M + n 2H O (x-1)+

2 n-1[M(OH)(H O) ] + 3H O


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Axit 1 Baz2 Baz1 Axit2

M: 2+Be , 2+Zn , 3+Al , 3+Fe , 3+Cr , 2+Cu

S d nh vy l v tt c cc ion trong dung dch nc u b hirat

ho. Vn chnh l cc ion hirat ho c lc axit hay baz mnh hn

nc khng. Nu lc axit hoc baz ca chng mnh hn nc th chng mi

c kh nng tham gia phn ng axit baz vi nc, ngha l tham gia phn

ng thu phn. Cn nu lc axit hoc baz ca chng yu hn nc th chng

ch tn ti trong dung dch nc di dng ion hirat ha. cc phn ng

trn, cho gn thng ngi ta hay vit ion n gin m khng vit ion

hirat ho.

Mt s cation kim loi hirat ho th hin lc axit manh hn nc rt

nhiu. l nhng cation c bn knh nh, in tch ln. Th d:

[Cu(H2O)4]2+

,[Al(H2O)6]

3+,[Fe(H2O)6]

3+, [Cr(H2O)6]

3+.Tham gia phn ng

thu phn kh mnh.

Th d, phn ng thu phn NH4NO3 v Al(NO3)3nh sau:

4NH + 2H O NH3 + 3H O

[Al(H2O)6]3+

+ 2H O [Al(OH)(H2O)5 ]2+

+ 3H O (nc 1)

[Al(OH)(H2O)5 ]2+

+ 2H O [Al(OH)2(H2O)4 ]+

+ 3H O (nc 2)

[Al(OH)2(H2O)4 ]+

+ 2H O [Al(OH)3(H2O)3 ] + 3H O (nc 3)

Th d: lm sch nc, ngi ta ho tan mt t phn nhm kali

K2Al2(SO4)3.24H2O vo mt lng ln nc. Do dung dch rt long, phn

ng thu phn ion Al3+xy ra n cng to ra [Al(OH)3(H2O) ] kt ta keo

hp th cc cht bn l lng v cc vi khun c trong nc lng xung y

lm trong nc.


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d) Mui ca baz yu v axit yu.

Thuc loi ny c mui xianua, axetat, cacbonat, sunfua ca cc kim

loi bn phi ca bng tun hon v ca ion amoni. Th d: Al 2S3,

Cr2(CO3)3, NH4CH3COO, NH4CN

Tr mui amoni ra, cc mui loi ny rt t tan nhng khi tan th phn

li hon ton thnh cc ion. Phn ng ca cc ion vi nc c th xy ra hon

ton do sn phm thu phn l cht kt ta, bay hi, hoc in li yu. Th d,

nhm sunfua khi tng tc vi nc to ra nhm hiroxit kt ta v kh

hirosunfua bay ln ch li rt t Al3+ v S2-trong dung dch:

Al2S3 (r) + 6 H2O(1) 2 Al(OH)3 + 3 H2S(k)

Mui amoni ca axit yu khi tantrong nc in li hon ton thnh cc

ion. Cc cation v anion ca chng u phn ng vi nc nhng mc c

khc nhau ph thuc vo mnh ca axit amoni v baz anion to thnh

mui . Th d phn ng thu phn amoni axetic:+

4NH + H2O NH3 ++

3H O +4a, NH

K = 5,6.10-10

-

3CH COO + H2O 3CH COOH +-OH -

3b, CH COOK = 5,7.10

-10

mnh ca axit +4NH v ca baz-

3CH COO gn nh nhau nn mi

trng ca dung dch gn nh trung tnh.

1.3.8.2. Tnh axit, baz ca dung dch mui.

a) Xt thu phn ca mui to thnh t baz mnh v axit yu.

Nh mc 1.3.8.1b thy anion gc axit mui loi ny l baz mnh

hn nc. Th d: i vi mui NaA, anion A-l baz mnh hn nc:

-A + H2O HA +-OH


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Phn ng thu phn lphn ng thun nghch nn c th p dng nh

lut tc dng khi lng cho cn bng thu phn trn v vit c phng

trnh ca hng s thu phn nh sau:

-

tp -

[HA][OH ]K =

[A ]

Ta thy hng s thu phn ca anion -A chnh l hng s baz, Kb,A-.

Ka,HA =2H O

K

T ta c th vit: tpK = Kb,A-= 2H

a, HA

KK

O (1.12)

Quan h ny cho php tnh c hng s thu phn, v gi tr Kathng

d dng thy trong cc bng tracu.

Phng trnh (1.12) cho thy hng s thu phn tpK t l nghch vi

hng s phn li axit ca axit HA. Nh vy, axit HA cng yu, Kacng nh th

Ktpca mui cng ln, ngha l s thu phn ca mui cng mnh.

Nh vy, hng s thu phn Ktpv thu phn tp u c th c

trng cho mc thu phn ca mui.

Bit hng s thu phn Ktpca anion A-, ta c th tnh pH ca dung

dch phn ng thu phn mui NaA tng t nh tnh pH ca dung dch

baz A .

Th d:Tnh nng ion -OH v pH ca dung dch NaCN 0,10M. Bit

Kaca HCN 250C l 6,2.10

-10..

i vi mui NaCN, ch c anion -CN l tham gia phn ng thu phn.

-CN + H2O HCN +-OH Ktp


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Nng ban u(mol/l) 0,10

Nng cn bng(mol/l) 0,10 -x x x

Vy: Ktp = 2- -14

H -5

- -10

a

K[HCN][OH ] 1.10= = =1,6.10

[CN ] K 6,2.10O

Thay nng cc cht vo ta c:

Ktp =2

-6x.x x =1,6.100,1 - x 1,10

( vi 0,10 x 0,1)

x = -[OH ] = 1,3.10-3

mol/l.

Ta thy rng : 0,10 x = 0,101,3.10-3 0,1 nh lm gn trn.

pOH = -lg1,3.10-10

= 2,89

pH = 142,89 = 11,11

Nh vy dung dch c mi trng kim .

b) Xt s thu phn ca mui to thnh t baz yu v axit mnh.

Nh ta thy mc1.3.8.1c cation kim loi mui loi ny to ra ion

hirat ho vi lc axit mnh hn nc. cho gn, ta vit ion n gin:

+ +

2 3M + 2H O MOH + H O

hoc + +4 2 3 3NH + H O NH + H O

Lp lun tng t nh trn ta s c kt qu:

2H

tp

b

KK =

KO

(1.13)


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v 2H Otpb

K =

K .C(1.14)

Phng trnh (1.13) cho thy hng s thu phn Ktp t l nghch vi

hng s phn li baz ca baz MOH hoc baz NH3.

Nh vy, baz cng yu, Kbcng nh th Ktpca mui cng ln, ngha

l s thu phn ca mui cng mnh.

Cn t phng trnh (1.14) ta cng thy: Khi nng ca mui cng nh

th thu phn ca mui cng ln, ngha l mui b thu phn cng mnh.

Da vo phng trnh (1.14) ta cng c th tnh c Ktp. Sau c th

tnh pH ca dung dch mui thu phn tng t nh tnh pH ca dung dch

axit yu .

Th d: Tnh nng ion H+v pH ca dung dch NH4Cl 0,10M. Bit

Kbca NH3 l 1,8.10-5. i vi mui ny ch c cation +4NH l tham gia phn

ng thu phn.

+

4NH + 2H O 3NH ++

3H O Ktp

Nng ban u (mol/l) 0,10 0 0

Nng cn bng (mol/l) 0,10-x x x

+ -14-103 3 2

+ -5

4 b

KH O[NH ][H O ] x.x 10K = = = = = 5,6.10[NH ] (0,10- x) K 1,8.10

vi 0,10 x 0,1 ta c:

2 -11 -6x = 5,5.10 x = 7,4.10 (r rng l 0,107,4.10-6 0,10).

pH = - lg[H+

]= -lg 7,4.10-6

= 5,14


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Dung dch c mi trng axit ng nh d on.

c) Xt s thu phn ca mui to thnh t baz yu v axit yu

Nh mc 1.3.8.1d ta thy, i vi mui ny,c cation M+v mui -A u

tham gia phn ng thu phn. +3H O v-OH sinh ra trong hai qu trnh thu

phn s phn ng vi nhau.

M+

+ 2 2H O MOH ++

3H O (a)

-A + 2H O HA +-OH (b)

+

3H O +-OH 2 2H O (c)

M+

+ 2H O +-A MOH + HA (d)

Phng trnh tng (d) l tng ca ba phng trnh trn v hng s

cn bng i vi phng trnh tng qut s bng tch cc hng s cn bng

ca ba phng trnh phn ng hp thnh:

i vi phng trnh (a) c: Ktp.M+ = 22

H O

b,H O

K

K

i vi phng trnh loi (b) ta c: -tp,AH2

a,HA

KK =

KO

i vi phng trnh loi (c) ta c:H O2

1K =

K

Vy i vi phng trnh tng qut (d) ta c:2 2H H

tp

b, MOH a,HA H2

K K 1K = . .

KK KO O

O, suy ra tpK =

2H

b a

K

K .KO

(1.15)

Tip theo ta c th tnh thu phn ca mui MA.

M+

+ -A + 2H O MOH + HA

Nng ban u(mol/l) C C


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Bin thin nng (mol/l) -tp

. C -tp

.C +tp

.C +tp

.C

Nng cn bng (mol/l) C - tp

.C C - tp

.C tp

.C tp

.C

Thay nng vo ta c:

tpK =2 2 2

tp tp

2 2 2

tp tp

( ) .C ( )=

C (1- ) (1- )

Trong trng hp tp


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Chng 2:

XY DNG H THNG BI TP HO HC V AXIT BAZ TRONG CHNG TRNH HO HC V C THPT

(NNG CAO)

2.1. Phn tch s hnh thnh v pht trin khi nim axit baz

trong chng trnh ha hc ph thng .

2.1.1 S hnh thnh khi nim axit baz cp THCS2.1.1.1 S hnh thnh khi nim axit baz lp 8

Hc sinh c lm quen vi tn gi axitbaz mt s bi hc v PTHH

v CTHH, tnh theo CTHH v PTHH (bi 21, bi 23,SGK lp 8).Tuy

nhin, n bi Nc (bi 36) , hc sinh bt u c hiu v axit baz c

th hn:

* Hnh thnh khi nim baz:

Th nghim: cho vo bt s (hoc ng nghim) mt cc nh vi sng -

canxi oxit CaO. Rt mt t nc vo vi sng. Nhng mt mu giy qu tm

vo dd nc vi. Hin tng xy ra?

Nhn xt: C hi nc bc ln, canxi oxit rn chuyn thnh cht nho

l vi ti - canxi hiroxit Ca(OH)2. Phn ng ta nhiu nhit. Nguyn nhn l

do c phn ng CaO ha hp vi nc:

CaO + 2H O

2NaOH + H2.

DD nc vi lm i mu qu tm thnh xanh. Tng t nh vy H2O

cng ha hp vi Na2O, K2Oto ra natri hiroxit NaOH, kali hiroxit

KOH


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Kt lun: Nh vy, hp cht to ra do oxit baz ha hp vi nc

thuc loi baz. DD baz lm i mu qu tm thnh xanh.

* Hnh thnh khi nim axit:

Th nghim: Nc ha hp vi iphotpho pentaoxit P2O5 to ra axit

photphoric H3PO4 :

P2O5 + 3H2O 2 H3PO4

DD axit H3PO4lm i mu giy qu tm thnh .

Nc cng ha hp vi nhiu oxit axit khc nh SO2 , SO3, N2O5to

ra axit tng ng.

Kt lun: Hp cht to ra do nc ha hp vi oxit axit thuc loi axit.

DD axit lm i mu qu tm thnh .

Tip sau , bi 37 (SGK 8):Axit Baz Mui hc sinh tip tc

c tm hiu v thnh phn, cng thc, phn loi v cch gi tn axit, baz.

* Axit:

Khi nim: Phn t axit gm c mt hay nhiu nguyn t hiro lin ktvi gc axit, cc nguyn t hiro ny c th thay th bng cc nguyn t kim

loi.

Cng thc:Gm mt hay nhiu nguyn t H v gc axit.

Phn loi :Da vo thnh phn phn t, axit c chia lm hai loi:

- Axit khng c oxi( HCl, H2S)- Axit c oxi ( H2SO4, H3PO4, HNO3, H2SO4)* Baz

Khi nim: Phn t baz gm c mt nguyn t kim loi lin kt vi

mt hay nhiu nhm hiroxit ( - OH).

Cng thc :Gm mt nguyn t kim loi (M) v mt hay nhiu nhm

hiroxit OH


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Phn loi: da vo tnh tan ca baz chia lm hai loi

- Baz tan c trong nc gi l kimVD : NaOH, KOH, Ca(OH)2,

- Baz khng tan trong ncVD : Cu(OH)2 , Mg(OH)2,

2.1.1.2 S cng c khi nim axit baz lp 9

Khi nim axit baz c cng c ngay chng 1- SGK 9 (chng 1:Cc

loi hp cht v c; bi 3,4,7,8: Tnh cht ha hc ca axit, ca baz v mt

s axit, baz quan trng )

* Axit:

1. Tnh cht ha hc

1.1.Axit lm i mu cht ch th mu: dd axit lm i mu qu tm

thnh

Trong ha hc, qu tm l cht ch th mu nhn bit dd axit.

1.2. Axit tc dng vi kim loi: DD axit tc dng c vi nhiu kimloi to thnh mui v gii phng kh hiro .

Ch : Axit nitric HNO3 v H2SO4c tc dng c vi nhiu kim loi,

nhng ni chung khng gii phng kh hiro (tnh cht ny s c hc

THPT )

1.3. Axit tc dng vi baz : Axit tc dng vi baz to thnh mui v

ncPhn ng ca axit vi baz c gi l phn ng trung ha

1.4. Axit tc dng vi oxit baz: Axit tc dng vi baz to thnh mui

v nc

Ngoi ra axit cn tc dng vi mui


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2. Axit mnh v axit yu :

2.1 Axit yu c cc tnh cht ha hc sau: phn ng chm vi kim loi,

vi mui cacbonat, dd dn in km

VD : HCl, HNO3 , H2SO4

2.2 Axit mnh c cc tnh cht ha hc sau: phn ng nhanh vi kim

loi, vi mui cacbonat, dd dn in tt

VD : H2S, H2CO3

3. Mt s axit quan trng

SGK HH 9 a ra bi tnh cht ha hc v cc ng dng quan trng ca

axit HCl v axit H2SO4. Tip theo v axit-baz l bi: Sn sut axit sunfuric

trong cng nghip

Tip theo , bi 12(SGK HH9), tnh cht ha hc ca axit baz

c cng c li qua: Mi quan h gia cc loi hp cht v c . bi ny,

hc sinh c h thng li mi quan h gia cc loi hp cht v c v nhng

phn ng ha hc minh ha cho mi quan h gia cc loi hp cht v cNh vy, kt thc chng trnh ha hc THCS, khi nim axit baz

mi ch dng li du hiu nhn bit. Quan nim v axit baz thng

nht cc axit baz thnh nhng nhm hp cht v c, hc sinh quen vi mt

s axit baz quen thuc v tnh cht in hnh m cha hiu c bn cht

ca chng, cha hiu r nguyn nhn tnh cht ca axit baz v mt nh

lng ca tnh cht . Mc d hc sinh bit c mt s axit baz mnh vyu quen thuc nhng cha hiu nh mt cch c h thng.

Mc ch khi nghin cu khi nim axit baz giai on ny l hc

sinh phn bit khi nim axit baz vi cc khi nim v cc hp cht v c

khc (oxit, mui). Hc sinh d dng nhn bit c nhng axit baz khi

thy r thnh phn H vOH trong phn t. Hc sinh nm c nhng tnh


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cht c bn c trng, cch nhn bit hai loi hp cht ny.Trong giai on

ny, hc sinh khng th thy +4NH cng l mt axit v NH3cng l mt baz

mc d n khng c thnh phn ha hc nh nh ngha c nghin cu.

2.1.2 S cng c khi nim axit baz chng trnh ha hc lp

10 THPT

chng trnh ha hc ph thng (v c), khi nim axit baz s

c xem xt mc cao v su hn. Tuy nhin, trong chng trnh ha

hc lp 10, hc sinh vn c tip tc cng c khi nim axit baz hc

THCS qua cc bi nghin cu v cc axit v baz c th (axit clohiric, axit

sunfuric )

Cng nh THCS, khi nim axit baz lp10 c cng c li sau

khi nghin cu l thuyt ch o. cc chng 1, 2, 3, 4 hc sinh ln lt

c nghin cu cc thuyt: Thuyt electron(chng 1,2); Lin kt ha hc

(chng 3); l thuyt v phn ng ha hc (chng 4).Khi nim axit baz sau khi c nghin cu l thuyt ch o c

cng c li mt cch n gin hn (nhc li) :

Bi 31 (SGK HH10- nng cao): Dung dch hiroclorua trong nc

(dung dch axit clohiric) l mt dung dch axit mnh. Nhng tnh cht chung

ca mt axit (lm qu tm, tc dng vi baz, oxit baz, tc dng vi

mui, tc dng vi kim loi) u th hin r nt dung dch axit HCl:

Mg(OH)2 + 2HCl MgCl2 + 2H2O

CuO + 2HCl CuCl2 + H2O

CaCO3 + 2HCl CaCl2 + H2O + CO2

Fe + 2HCl FeCl2 + H2


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Hay trong bi 32 (SGK HH10- nng cao) :

S bin i tnh cht trong dy axit c oxi ca clo c biu th bng

s sau :

Tnh ben v tnh axit tang

HClO HClO2 HClO3 HClO4

Kha nang oxi ha tang

R rng, do c trang b y hn c s l thuyt nn khi c cng

c khi nim axit baz, hc sinh cnghin cu su v rng hn trn cs nhng khi nim c hc trc

2.1.3 S pht trin khi nim axit baz chng trnh ha hc

lp 11 THPT.

Chng trnh HH 11 c bt u vi Thuyt in li. y l mt

thuyt quan trng trong h thng l thuyt ha hc v c bit quan trng i

vi s pht trin khi nim axit baz HHPT.

c l thuyt in li soi sng, bi 3 a ra ni dung Axit, baz v

mui . Trong chng trnh HH 11 nng cao, hc sinh c nghin cu ng

thi thuyt axit baz ca Areniuyt v Bronstet-Lauri trong khi chng

trnh HH 11 c bn, hc sinh ch nghin cu thuyt axit baz ca Areniuyt.

Khi nim axit baz, phn ng trung ha ca Areniuyt n gin, d

gii thch, hc sinh d hiu nn n c s dng lm ni dung xut pht

hc cc l thuyt khc sau ny.

Tuy nhin, hc sinh d dng nhn thy thuyt axit baz ca Areniuyt

tha nhn s tn ti c lp ca ion H+ trong H2O (mu thun vi s hirat

ha H+ca H2O c hc bi 1.2: C ch ca qu trnh in li). Ngoi


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ra, thuyt axit baz ca Areniuyt cn gp nhiu kh khn v mu thun

khc i hi mt hc thuyt khc u vit gii quyt cc bt cp trn.

Thuyt axit baz ca Bronstet - Lauri c gii thiu gii quyt cc

mu thun ca Areniuyt m khng ph nhn Areniuyt (cc axit baz ca

Bronstet-Lauri vn bao gm cc axit baz ca Areniuyt) . Vai tr ca dung

mi trong qu trnh phn li phn t thnh ion nh hng n tnh axit baz

v mnh yu ca axit baz .

im khc bit ln nht khi nim axit baz giai on ny l n

c a ra cng vi cch nh gi nh lng tng ng. Nh vy hc sinh

c th nh gi mnh yu ca axit baz mt cch nh lng chnh xc

v hiu nhng nh gi trc y c hc.

Vic a vo chngtrnh ng thi hai hc thuyt ca cng mt khi

nim c tc ng ln n hc sinh. N khng ch cung cp cho hc sinh h

thng l thuyt thng nht m cn gip hc sinh thy c lch s pht trin

ca khi nim axit baz .

Nhvy khi nim v phn ng axitbaz c m rng v dung

lng v khc su v ni dung tr thnh mt b phn kin thc l thuyt c

s, l cng c hc sinh nghin cu s tng tc ca cc ion trong dd cc

cht in li, tnh axit hay baz ca cc dd trong cc dung mi khc nhau. Tuy

nhin do mc ch ca chng trnh ho hc THPT ch dng mc trang b

kin thc c bn, nn cn nhiu ni dung su hn v axitbazcha c cp n nh: thuyt axitbazca Liuyt; thuyt cc h dung mi

Trong SGK ch a thm vo tnh baz ca cc amin v anilin nhng

tnh baz vn c gii thch bng thuyt Brosntet-Lauri. Tnh axit th hon

ton s dng Brosntet-Lauri (ca hp cht phenol, ca cc axit cacboxylic )


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2.1.4 S pht trin v cng c khi nim axit baz chng trnh

ha hc lp 12 THPT.

Phn ha hcv c, cc bi 29, 31, 34, 39, 41, tnh axit baz tip

tc c nhc li mc d khng ni theo thuyt no nhng hc sinh vn c

hiu theo Bronstet-Lauri .

VD: -3HCO + H+ H2O + CO2

Trong phn ng ny, ion -3HCO nhn proton, th hin tnh cht ca baz

Ca(OH)2 Ca2+

(dd) + 2 -OH (dd)

DD canxi hiroxit c nhng tnh cht chung ca mt baz tan (tc dng vi

oxit axit, axit , mui)

Sau khi kt thc chng trnh HHPT, khi nim axit baz c

nghin cu mt cch tng i y qua nhiu ln nghin cu cc thuyt v

khi nim. Ngoi ra, axit baz cn c nghin cu qua cc bi c th v

cht (cc axit, baz c th, cc cht c tnh cht axit , baz hoc lng

tnh). Khi nim axit baz c xy dng theo m hnh xoy c v c

theo m hnh ng thng, cng vi vic kt hp mt cch kho lo bi tp

ha hc s gip hc sinh bit, hiu, vn dng v nh gi khi nim axit

baz mt cch nhanh v chnh xc nht.

2.2. C s xy dng v sp xp bi tp

2.2.1 Cn c vo s hnh thnh v pht trin khi nim

Cn c vo s hnh thnh v pht trin khi nim xy dng v sp xpbi tp thnh ba loi bi tp:

- Bi tp hnh thnh khi nim axit baz.

- Bi tp cng c khi nim axit baz.

- Bi tp m rng khi nim axit baz.

- Bi tp tng hp v axit baz.


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2.2.2 Cn c vo cu trc ni dungchng trnh SGK THPT

Cn c vo cu trc ni dung chng trnh SGK THPT xy dng v

sp xp bi tp thnh ba loi bi tp:

- Bi tp cho lp 10

- Bi tp cho lp 11

- Bi tp cho lp 12

2.2.3 Cn c vo c s phn loi bi tp ha hc

Cn c vo cs phn loi bi tp ha hc xy dng v sp xp bi tp

thnh hai loi bi

- Bi tp t lun

- Bi tp trc nghim khch quan

2.3. H thng bi tp ha hc.

2.3.1 Bi tp hnh thnh khi nim axit baz

2.3.1.1 Bi tp hnh thnh khi nim axit bazlp 10

a.Bi tpt lunBi 1.Hy vit cc PTHH ca phn ng trong mi trng hp sau:

a) Km oxit v axit nitric

b) ng (II) oxit v axit sunfuric

c) St v axit clohiric

d) Natri cacbonat v axit sunfuric

e) Nhm hiroxit v axit clohiricf) Lu hunh (IV) oxit v natri hiroxit

Bi 2. Trong cc dy cht di y, dy cht no gm cc cht u tc dng

c vi dung dch HCl ? Vit PTHH xy ra?

a) Fe2O3 , KMnO4 , CO2

b) K , CuO , Ba(OH)2


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c) CaCO3 , FeO , Cu

d) BaSO4 , NaOH , Mg(OH)2

Bi 3. Trong cc dy cht di y, dy cht no gm cc cht u tc dng

c vi dung dch NaOH ? Vit cc PTHH xy ra ?

a) BaO , HCl , FeCl2b) CO2 , HNO3 , FeCl3c) AgCl , H2SO4 , SO2d) KNO3 , HCl , Al2O3

Bi 4. C nhng cht sau: Mg, Mg(OH)2, KOH, Fe(OH)3 , FeSO4 , KCl, HCl.

Hy chn cht thch hp in vo mi s phn ng sau v lp PTHH.

a) 0t Fe2O3 + H2O

b) H2SO4 + K2SO4 + H2O

c) H2SO4 + MgSO4 + H2O

d) NaOH + NaCl + H2O

e) + CO2 K2CO3 + H2O

Bi 5.C nhng cht: CuO, BaCl2, Zn, ZnO. Cht no ni trn tc dng vi

dung dch HCl, dung dch H2SO4 long sinh ra :

a) Cht chy c trong khng kh?b) Dung dch c mu xanh lam?c) Cht kt ta mu trng khng tan trong nc v axit?d) Dung dch khng mu v nc?

Vit cc PTHH xy ra.

Bi 6. Hy tm CTHH ca nhng axit c thnh phn nguyn t nh sau:

a) H : 2,12% ; N: 29,8 % ; O : 68,08%b) H : 3,7% ; P: 37,8% ; O : 58,5%


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Bi 7. C nhng baz: 2Cu(OH) , KOH, 3Fe(OH) , NaOH , 3Al(OH) ,

2Mg(OH) , 2Ba(OH) , 2Zn(OH) . Hy cho bit nhng baz no :

a) Tc dng c vi dung dch HCl?b) B phn hu nhit cao?c) Tc dng c vi kh 2CO ?d) Tc dng c vi dung dch 3FeCl ?e) i mu qu tm thnh xanh?

Bi 8.Cho 23,2 gam hn hp Fe, Cu tc dngvi HCl d, thu c 6,72 lt

kh 2H (ktc).Xc nh khi lng v nng % theo khi lng cc kim

loi trong hn hp u.

Bi 9. Cho mt lng bt st d vo 50 ml dd axit sunfuric. Phn ng xong,

thu c 4,48 lt kh hiro (ktc).

a) Vit phng trnh ho hc.b) Tnh khi lng st tham gia phn ng.c) Tnh nng mol ca dung dch axit dng.

Bi 10.C ba l ng ba dung dch: HCl, 2 4H SO , 3KNO . Hy nhn bit mi

cht bng phng php ho hc.

Bi 11. T cc cht sau y: Na, BaO, CaO. Hy vit cc phng trnh phn

ng iu ch cc baz tng ng.

Bi 12.T S, Oxi, nc, mui n,v cc cht xc tc cn thit, cc dng c

th nghim khc, vit cc phng trnh phn ng iu ch axit sunfuric v axit

clohiric.

Bi 13. Nu v gii thch cc hin tng xy ra (nu c) khi cho:

- Kim loi st vo axit sunfuric long.

- Mui st (III) clorua tc dng vi dung dch natri hiroxit .

- Kim loi ng tc dng vi dung dch axit clohiric.


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- Dung dch natri cacbonat tc dng vi dung dch axit sunfuric long.

- Dung dch axit sunfuric long tc dng vi dung dch natri hiroxit.

- Dung dch axit sunfuric long tc dng vi dung dch bari hiroxit.

Bi 14.Hon thnh cc qu trnh bin i sau:

2 2 3 2 4Cl HCl BaCl Ba(NO ) BaSO

Bi 15.Trong s cc phn ng sau y, phn ng no l phn ng axit-baz?

Ti sao?

2 3 2 2Na SO +2HCl 2NaCl+H O+SO

3 3 2KHCO +NaOH NaKCO +H O

2 2FeCl +2KOH Fe(OH) +2KCl

2 4 2 4 3 23H SO + 2Al Al (SO ) +3H

Bi 16. Cho 11 gam hn hp gm Fe v Al tc dng vi axit sunfuric long

d thu c 8,96 lt kh hiro(ktc).

1.Tnh phn trm khi lng mi kim loi trong hn hp u.

2. Tnh th tch dung dch axit sunfuric 1M dng bit dng d

12% so vi l thuyt.

Bi 17.Trung ho hon ton 150 ml dung dch axit 2 4H SO 1,2M bng dung

dch 2Ba(OH) 1M.

1. Tnh th tch dung dch 2Ba(OH) dng cho phn ng trn.2. Tnh khi lng cht kt ta thu c sau phn ng.

Bi 18.Ho tan ht m gam st (II) sunfua trong dung dch 2 4H SO long thu

c x mol kh. Cng ho tan ht m gam mui trong dung dch 2 4H SO c

nng th sinh ra bao nhiu mol kh?

Bi 19.Cho 5,19 gam hn hp X gm cc kim loi Al, Ag, Fe tc dng vi

dung dch 2 4H SO long, d sinh ra 2,352 lt kh (ktc). Cng cho 5,19 gam


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hn hp X trn tc dng vi dd 2 4H SO c, nng d th thu c 2,912 lt kh

2SO (ktc). Tnh hm lng phn trm ca cc kim loi trong hn hp X.

Bi 20. Ho tan ht 16 gam hn hp X gm Cu v CuS trong dung dch

2 4H SO c nng thu c 11,2 lt 2SO (ktc).

1. Vit PTHH ca phn ng xy ra.2. Tnh khi lng mi cht trong hn hp X.

b. Bi tp trc nghim khch quan

1. Cho mt lng d axit clohidric tc dngvi 6,54g km (Zn = 65,47). Th

tch hiro thu c (o ktc) l bao nhiu?

A. 1,14 lt B. 2,24 lt C. 4,48 lt D. 3,36 lt

2. Nh 100 cm3dung dch axit HCl c cha 36,5g HCl trong 1 lt vo 1 lng

canxi cacbonat d. Cho bit tn cht kh bay ra

A. Clo B. Hiro C. Cacbonic D. Cacbonat

3. Ngi ta cho axit clohiric tc dng vi nhm v oc 20 lt hiro ( ktc)

(Al = 27; Cl = 35,5). Tnh khi lng Al b axit clohiric n mn

A. 16,1 g B. 161 g C. 265 g D. 26,5 g

4. Axit H2SO4long tc dng vi Zncho sn phm no?

A. Sunfat km v kh hiro B. Sunfua km v kh hiro

C. Sunfat km v kh sunfur D. Sunfua kmv kh sunfur

5.Cho 14,7g axit sunfuric long tc dng vi Fe d (Fe=56). Tnh th tch kh

bay ra v cho bit tn cht kh.

A. 1,68 lt H2 B. 3,36 lt SO2 C. 3,36 lt H2 D. 1,68 lt SO2

6. axit sunfuric va vo mt dung dch bari clorua cha 52g mui ny.

un nng cho nc bay hi, cht rn cn li c em cn (Ba=137). Cht

rn ny cn nng bao nhiu?

A. 58,25g B. 121g C. 12,1g D. 582,5 g


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7. Cho 8gam NaOH rn tan va trong dung dch 2 4H SO 0,1 M thu c

dung dch A.

a) Th tch dung dch axit dng l :

A. 1 lt. B. 0,1 lt C. 10 ml D. 100 ml

b) Khi lng cht rn thu c sau khi c cn dung dch A l:

A. 1,42 gam B. 14,2 gam C. 142 gam D. 100 gam

8. Cho dung dch 2Ba(OH) 0,2 M tc dng vi 200 ml dung dch mui natri

sunfat 0,1 M.

a ) Th tch dung dch 2Ba(OH) dng thu c kt ta ln nht l:

A. 1lt. B. 0,1 lt C. 10 ml D. 100 ml

b) Khi lng kt ta thu c sau phn ng l :

A. 2,33 gam B. 4,66 gam C. 3,12 gam D. 31,2 gam

9.Kt ta hon ton 150 ml dung dch 3FeCl 1M bng mt lng dd NaOH

va . Sau nung kt ta n khi lng khng i, c cht rn E. Khi

lng cht rn E l:

A. 36 gam B. 24 gam C. 12 gam D. 15 gam

10.C cc dung dch sau ng trong cc ng nghim: HCl, 2Ba(OH) , 2 4H SO .

C th nhn bit c cc dung dchtrn bng cch:

A. Qu tm B. Phenolphtalein C. HCl D. Ha cht khc

11.Trong phn ng no sau y, axit ch ng vai tr cht kh:

A. 2 2Cl +2HBr 2HCl+Br

B. 3 22Al+6HCl 2AlCl +3H

C. 2 2 22Cu +O + 4HCl 2CuCl +2H O

D. 2 2 2 2MnO +4HCl MnCl +Cl +2H O


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12.Cho 2 gam hn hp A gm Mg, Al, Fe, Zn tan ht trong dd HCl to ra

0,05 mol kh. Cng cho 2 gam hn hp A tc dng vi2Cl (d) to ra 5,763

gam hn hp mui. Trong A, % v khi lngca st l:

A. 14 % B. 16,8 % C. 19,2 % D. 22,4 %

13.Khi lng axit sunfuric c th thu c t 1,6 tn qung c cha 60%

2FeS . Bt hiu sut cc phn ng u t 100%.

A. 1568 kg B. 1,725 tn C. 1200 kg D. 6320 kg

14. Ho tan hon ton 20g hn hpMg v Fe bng dung dch HCl d,sauphn ng thu c 11.2l kh (ktc) v dung dch X. C cn dung dch X th

thu c bao nhiu gam mui khan?

A. 71,0 gam. B. 90,0 gam C. 91,0 gam D. 55,5 gam

15.Cho cc cht sau: Na, 2H O , S, 2O . S hp cht v c c th iu ch

c l:

A. 3 B. 4 C. 5 D. 7

16.Mt s ng dng ca axit HCl l:

A. iu ch cc mui clorua.

B. Ch bin thc phm, dc phm.

C. Lm sch b mt kim loi trc khi hn.

D.Ty g kim loi trc khi sn, trng, m kim loi.

E Tt c cc p n trn

17.Trong cng nghip c th sn xut NaOH bng cch:

A. in phn dd NaCl c mng ngn B. Cho 2Na O tc dng vi 2H O .

C. Cho 2Ba(OH) td vi 2 4Na SO . D. Cho Na tc dng vi 2H O


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18.Cht no trong s nhng thuc th sau y c th dng phn bit dung

dch natri sunfat v dung dch natri cacbonat:

A. Dung dch bari clorua B. Dung dch axit clohiric

C. Dung dch ch nitrat D. Dung dch bc nitrat

19.Mt hp cht c thnh phn theo khi lng: 35,96% S; 62,92% O v

1,12 % H. Hp cht ny c cng thc l:

A. 2 3H SO B. 2 4H SO C. 2 2 7H S O D. 2 2 8H S O

20.Dy axit no sau y c sp xp ng theo th t tnh axit gim dn?

A. HCl, HBr, HF B. HBr, HI, HF, HCl

C. HI, HBr, HCl, HF D. HF, HCl, HBr, HI

2.3.1.2 Bi tp hnh thnh khi nim axit baz lp 11

a. Bi tpt lun.

Bi 21.Cc kt lun sau ng hay sai? Nu sai hy sa li cho ng:

1. C nhng baz lng tnh. VD: ` 2Zn(OH) , 3Al(OH) .

2. Trong phn t baz, lun c nhm (-OH) .

3. Phn ng axit-baz l phn ng gia axit v baz

4. Cht in li l nhng cht tan trong nc v dn in.

5. Axit l nhng cht m phn t c cha nguyn t H.

6. Baz l nhng cht c kh nng nhng electron.

7. CuO l mt baz .

8. Ni 3+Al l mt axit.

9. 2H O l mt cht khng in li.

Bi 22.Cc cht cho sau y l axit, baz, lng tnh hay trung tnh? (theo

thuyt axit-baz ca Bronstet-Lauri). Hy gii thch.2-

3CO , 2 4H SO ,-

3CH COO , NaOH, 3NH ,+

4NH .


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Bi 23.Vit phng trnh in li ca cc axit mnh HI v 4HClO ; cc axit

yu: 2HNO ; 2 3H SO ; cc mui: 2 4Na SO , 2 3K HPO , 4KHSO , 3 2 2 4[Ag(NH ) ] SO

Bi 24.Trong cc phn ng di y, cc cht tham gia phn ng no ng

vai tr l axit, cht no ng vai tr l baz (theo Bronstet-Lauri)

1. CuO + 2HCl 2CuCl + 2H O

2. NH4Cl + NaOH NaCl + 3NH + 2H O .

3. 2 3Fe(OH) + 3 2 4H SO 2 4 3Fe (SO ) + 6 2H O

4. 3CH COOH + 3NH 3 4CH COONH

Bi 25.Vit PTHHchng t nhm hiroxit 3Al(OH) l cht lng tnh.

Bi 26.Hon thnh cc PTHH sau dng phn t v dng ion thu gon. Nhn

xt xem cc phn ng c phi l phn ng axitbazhay khng?

1. Al + 3HNO 3 3Al(NO ) + NO + 2H O

2. HCl + CaCO3

2CaCl + 2CO + 2H O

3. 2Zn(OH) + 2NaOH 2 2Na ZnO + 2 2H O

4. 3 4Fe O + 4 2 4H SO 4FeSO + 2 4 3Fe (SO ) + 4 2H O

Bi 27. Ch dng qu tm, hy phn bit cc dung dch trong cc ng nghim

ring bit sau: 2 4H SO , HCl, NaOH, KCl, 2BaCl .

Bi 28.Trn ln 50 ml dung dch NaOH 0,2 M vi150 ml dung dch HClc dung dch A.

1.Tnh nng mol/l cc ion trong dung dch A .

2. Tnh pH ca dung dch A.


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Bi 29. ho tan hon ton 15 gam hn hp A (gm Mg v Fe) ngi ta

phi dng V ml dd3HNO long 0,5M. Sau phn ng thu c 8,4 lt kh NO

duy nht (ktc).

1. Tnh % khi lng mi kim loi trong A.

2. Xc nh V.

Bi 30.Trung ho hon ton 1000ml dung dch X gm HCl v 2 4H SO cn

500 ml dung dch 2Ba(OH) 0,1M, thu c 5,825 gam kt ta.

1. Tnh nng mol/l mi axit trong dung dch X.2. Tnh pH ca dung dch X v ca dung dch 2Ba(OH)

3. Tnh nng mol/l ca cc ion trong dung dch thu c sau khi trung ho

(th tch dd thay i khng ng k)

Bi 31. Thm 100ml dung dch 2 4H SO 0,2M vo bnh c cha sn 100ml

dung dch X gm NaOH 0,12 M v 2Ba(OH) 0,15 M.

1.Tnh khi lng kt ta thu c

2. Tnh pH ca dung dch thu c sau phn ng

Bi 32. Vit PTHH xy ra di dng phn t v ion:

1. 4 2 4(NH ) SO + 2Ba(OH)

2. x yFe O + 2y HCl

3. NaOH + 3NaHCO

Bi 33.Tnh th tch dung dch HCl 0,5M cha s mol +H bng s mol +H

c trong 0,3 lt dung dch 3HNO 0,2 M.

Bi 34. Chia 19,8 gam 2Zn(OH) lm hai phn bng nhau:

1. 150 ml dung dch 2 4H SO 1M vo phn mt. Tnh khi lng mui to

thnh.


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2. 150 ml dung dch NaOH 1M vo phn hai. Tnh khi lng mui to

thnh.

Bi 35.D on hin tng v gii thch bng cc phn ng ho hc khi:

1. Nh t ttng git dung dch NaOH (cho n d) vo dung dch 3AlCl ?

2. Nh t t tng git dung dch 3AlCl (cho n d) vo dung dch NaOH?

3. Nh t t tng git dung dch HCl vo bnh cha dung dch 2 3Na CO v

khuy u.

4. Nh t t vi git dung dch2 3Na CO vo bnh cha dung dch HCl

Bi 36.Cho vi git qu tm vo dung dch 4NH Cl , 3CH COONa , 2 4Na SO ,

KCl, 4NaHSO . Dung dch chuyn mu g? Ti sao?

Bi 37.Vit PTHHdi dng phn t ca cc PTHH c phng trnh ion thu

gn nh sau:

1. + -3 2H O + OH H O

2. + 2+3 2 22H O +Mg(OH) Mg +4H O

3. + -4 3 2NH +OH NH +H O

4. - - 2-3 3 2HCO +OH CO + H O

Bi 38.C a gam hn hp bt X gm CuO v 2 3Al O .Ngi ta thc hin cc

th nghim sau:

+ Th nghim 1: Cho X phn ng hon ton vi dung dch HCl, c cn

dung dch th thu c 4,02 gam cht rn khan.

+ Th nghim 2: Cho X phn ng va vi bt cacbon nhit cao

th thu c 0,112 lt kh (ktc).

Tm a

Bi 39.Cho 500 ml dung dch amoniac c ho tan 4,48 lt kh 3NH (ktc) tc

dng vi 450 ml dung dch 2 4H SO 1M.


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1. Vit cc PTHH xy ra.

2. Tnh nng mol/l ca cc ion trong dung dch thu c. Coi cc cht

in li hon ton thnh ion v b qua s thu phn ca ion +4NH .

Bi 40.C cc l khng dn nhn ng ring bit tng dung dch long ca

cc cht: 3KNO , 3HNO , 2 4K SO , 2 4H SO , KCl, HCl.

Hy phn bit mi cht trn bng phng php ho hc.

b. Bi tp trc nghim khch quan

21.Mt dung dch c [ -OH ]= -51,75.10 . Mi trng ca dung dch ny l:

A. Axit C. Kim

B. Trung tnh D. Khng xc nh c.

22.Trong dung dch HCl 0,1 M, tch s ion ca nc l:

A. + -[H ].[OH ] > -141,0.10 A. + -[H ].[OH ] < -141,0.10

B. + -[H ].[OH ] = -141,0.10 D. Khng xc nh c.

23.Cho cc phn ng sau:

A. HCl + 2H O -Cl + +3H O (1)

B. 3NH + 2H O +

4NH -OH (2)

C. 4CuSO + 5 2H O 4CuSO .5 2H O (3)

D. -3HSO + 2H O +

3H O +2-

3SO (4)

D. -3HSO + 2H O 2 3H SO +-OH (5)

Theo thuyt Bronstet-Lauri, 2H O ngvai tr l axit trong cc phn ng:

A. (1), (2) , (3) B. (2), ( 5)

C. (2), (3), (4), (5) D. (1), (3), (4)

24. Theo Bronstet-Lauri, kt lun no sau y l ng nht?

A.Axit l cht m phn t c cha nguyn t HiroB.Axit l cht in li mnh


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C.Axit tc dngc vi mi bazD. Axit l cht c kh nng cho proton.

25. Theo Bronstet-Lauri, kt lun no sau y khng ng?

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