CHUYN NHN BIT MT S CHT V C A. Nhn bit cc cht kh: 1. nhn bit
SO2(lu hunh ioxit) - lm c nc vi trong- lm qu tm m ha SO2+ H2O H2SO3
- lm mt mu dung dch brom hoc KMnO4 5SO2+ 2KMnO4+ 2H2OK 2SO4+
2MnSO4+ 2H2SO4 SO2+ 2H2O + Br 2H2SO4+ 2HBr - To bt mu vng vi dung
dch H2S SO2+ H2S 3S + 2H2O - Dung dch I2: Nht mu vng ca dung dch I2
SO2+ I2+ 2H2O H2SO4+ 2HI 2. nhn bit NH3(amoniac) - lm qu tm m ha
xanh- to khi trng vi HClc NH3+ HClc NH4Cl (khi trng tinh th) - lm
dung dch phenolphtalein t mu tm hng chuyn sang khng mu- to kt ta
trng xanh vi dung dch mui Fe 2+(do NH3+ H2O NH4OH c gc OH) 2NH3+
Fe2++ 2H2O Fe(OH)2(trng xanh) + 2NH4- dd amoniac c th ha tan
Cu(OH)2, Zn(OH)2, AgCl ... (to phc vi hiroxit hocmui ca Cu, Zn, Ag)
4NH3+ Cu(OH)2 [Cu(NH3)4](OH)2 4NH3+ ZnSO4 [Zn(NH3)4]SO4 2NH3+ AgCl
[Ag(NH3)2]Cl - dd amoniac lm CuO (en) chuyn thnh Cu () 2NH3+ 3CuO
3Cu + N2+ 3H2O 3. nhn bit CO2(cacbon ioxit) - Lm c nc vi trong - a
que dim vo th que dim tt 4. nhn bit O3(ozon) - Lm xanh giy tm dung
dch KI v h tinh bt O3+ 2KI + H2O 2KOH + O2 + I2 I2sau khi sinh ra
th lm xanh giy tm h tinh bt
5. nhn bit CO (cacbon monooxit) - Lm vn c dung dch PbCl2 CO +
PbCl2+ H2O Pb + 2HCl + CO2 - lm CuO (en) thnh Cu ()CO + CuO Cu +
CO2 6. nhn bit kh HCl (hiro clorua) - lm qu tm m ha - to kt ta vi
AgNO3, Pb(NO3)2 - to khi trng vi NH3 7. nhn bit kh O2(oxi) - lm que
dim bng chy - chuyn Cu () thnh CuO (en) 2Cu + O2 2CuO 8. nhn bit
H2(hiro) - chy vi ngn la mu xanh nht km theo ting n nh. Cho sn phm
i qua CuSO4 rn khan khng mu chuyn thnh mu xanh 2H2+ O22H2O CuSO4+
nH2O CuSO4.nH2O - chuyn CuO (en) thnh Cu () CuO + H2 Cu + H2O 9.
nhn bit Cl2(clo) - mu vng lc, mi sc - lm qu tm m mt mu Cl2+ H2OHCl
+ HClO (c tnh ty mu) - Lm xanh giy tm dung dch KI v h tinh bt Cl2+
2KI 2KCl + I2 - lm mt mu dung dch brom 2Cl2+ Br2+ 6H2O2HBrO3+ 10HCl
10. nhn bit H2S (hiro sunfua) - mi trng ung - lm qu tm m ha - to kt
ta en vi Pb(NO3)2, Cu(NO)3 Pb(NO3)2+ H2S PbS+ 2HNO3 Cu(NO)3+ H2S
CuS+ 2HNO3 - lm mt mu dung dch Br2 hoc KMnO4 H2S + 4Br2+ 4H2O8HBr +
H2SO4 -To bt mu vng vi dung dch SO2
SO2+ H2S 3S + 2H2O -to kt ta vng vi HNO3 (long) 3H2S + 2HNO3
(long) 3S + 2NO + 4H2O 11. nhn bit CH4 (metan) - lm CuO (en) thnh
Cu () CH4+ 4CuO 4Cu (mu ) + CO2 + 2H2O - chy trong oxi to kh lm c
nc vi trong CH4+ 2O2 CO2+ 2H2O 12. nhn bit SO3(lu hunh trioxi) - to
kt ta vi dung dch BaCl2 SO3+ H2O + BaCl2 BaSO4+ 2HCl - lm qu tm m
ha SO3+ H2O H2SO4 13. nhn bit NO2(nit ioxit) - ha tan kim loi hoc
lm qu tm ha trong nc khi sc NO2v O2vo 2NO2+ H2O + O2 2HNO3 8HNO3+
3Cu 3Cu(NO3)2+ 2NO + 4H2O - lm qu tm m ha 3NO2+ H2O 2HNO3+ NO 14.
nhn bit NO (nit monooxit) - khng mu - chy trong O2to ra kh mu nu
2NO + O22NO2(mu nu) - sc vo dd FeSO420% th thu c dd mu thm NO +
FeSO4(20%) Fe(NO)(SO4) 15. nhn bit gc NO3-(gc nitrat) - khi un nh
vi dung dch axit v vn ng, th vn ng tan ht, dung dch sau phn ng c mu
xanh (CuSO4) v to kh c mi hc (NO) 3Cu + 2NO3-+ 8H+3Cu+ 2NO+ 4H2O
16. nhn bit H2O2(oxi gi) -Lm xanh giy tm dung dch KI v h tinh bt
H2O2+ 2KII2+ 2KOH - gii phng bc khi tc dng vi Ag2O Ag2O + H2O22Ag +
H2O+ O2 17. nhn bit Br2(brom)
- cht lng mu nu -b nht mu bi Clo, SO2, H2S 5Cl2+ Br2+ 6H2O 10HCl
+ 2HBrO3 SO2+ 2H2O + Br2H2SO4+ 2HBr H2S + 4Br2+ 4H2O8HBr + H2SO4
18. nhn bit F2(flo) - cht kh mu lc nht - tc dng vi dd NaOH 2F2+
2NaOH2NaF + H2O + OF2+ OF2 l cht kh khng mu, c mi c bit, rt c. L
cht oxi ha mnh, tc dng hu ht vi cc kim loi v phi kim to thnh oxit v
florua. OF2+ 2Cu CuO + CuF2(lm Cu CuO en) OF2+ P P2O5+ PF5(cht rn
sau phn ng + H2O dd lm qu tm ho ) - nc khi un nng s bc chy trong
flo, gii phng oxi. 2F2+ 2H2O 4HF + O2 19. nhn bit I2(iot) - iot l
cht rn mu tm nht - khi un nng, it thng hoa to hi mu tm - Iot to
thnh vi h tinh bt mt cht c mu xanh 20. nhn bit H2O (hi nc)-hi nc lm
cho CuSO4(khan, mu trng) chuyn sang mu xanh CuSO4+ nH2O CuSO4.nH2O
(mu xanh) 21. nhn bit S (lu hunh) - lu hunh l cht rn mu vng - t
trong oxi cho kh c mi hc, lm c nc vi trong S + O2 SO2 SO2+ Ca(OH)2
CaSO3+ H2O - tan trong cc axit mnh nh H2SO4n, HNO3(c) S + 2H2SO4n
3SO2 + 2H2O S + 6HNO3 (c) H2SO4+ 6NO2 + 2H2O 22. nhn bit P(photpho)
- photpho c 2 loi: photpho v photpho trng - t chy to ra P2O5 tan
trong nc thnh dd lm qu tm 4P + 5O2 2P2O5
P2O5+ 3H2O 2H3PO4 - tan trong cc axit mnh nh H2SO4n, HNO3(c) 2P
+ 5H2SO4n 5SO2 + 2H3PO4+ 2H2O P + 5HNO3 (c) H3PO4+ 5NO2 + H2O 23.
nhn bit C (cacbon) - cacbon l cht rn mu en (tr kim cng) - t chy to
kh lm c nc vi trong - tan trong cc axit mnh nh H2SO4n, HNO3(c to kh
lm c nc vi trong C + O2 CO2 C + 2H2SO4n CO2 + 2SO2 + 2H2O C + 4HNO3
(c) CO2 + 4NO2 + 2H2O
