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8/19/2019 Soap and Water
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© Boardworks Ltd 20091 of 55
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The Earth’s water
It is estimated that there are 1,380 million km 3 of water onthe Earth.
Howe er, onl! 3" of the Earth#s water is fresh. $he remainin%9&" is saltwater, and forms the seas and o'eans.
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The water cycle
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Events in the water cycle
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Why is water so important?
*ater is e+tremel! im ortant to life on Earth and is also -sed! h-mans in a wide ran%e of a'ti ities.
transport coolants
washing
solvents
fishing leisure
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How is water treated?
*ater for o-r homes is treated to make it safe for drinkin% !the followin% s!stem/
s- lied tohomes, offi'esand fa'tories
'hlorine added filter eds
settlement tank
'hemi'als added whi'h'om ine with dirt toform a re'i itate
water from reser oir
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Stages in water treatment
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What is desalination?
In some 'o-ntries, there is not eno-%h rainwater to 'olle't inreser oirs. Instead, the ro'ess of desalination is -sed tomake freshwater from seawater.
an !o- think of an! ad anta%es and disad anta%esof desalination
$he sim lest
method ofdesalination isto distil thewater, lea in%the salt ehind.
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Why is fluoride added to water?
In some 'o-ntries, fl-oride is added to drinkin% water in theform of he+afl-orosili'i' a'id H
2i4
). In the 67, a o-t 10"
of homes re'ei e water with added fl-oride.
4l-oride has een ro en to stren%then tooth enamel, whi'hhel s to re ent tooth de'a!.
'ientists first made a link etween fl-oride and teeth inthe 1930s. *hat e iden'e do !o- think the! looked at
4l-oride o''-rs nat-rall! in some water s- lies,and is also nat-rall! resent in tea.
ost tooth astes also'ontain added fl-oride.
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Should fluoride be added to our water?
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Voting: fluoride in drin ing water
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!issolving words
If a s- stan'e : e dissol ed it is 'alled ;;;;;;;;;; .
If a s- stan'e ::
an !o- fill in the missin% words in the senten'es elow
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the amount of a substance that will dissolve in" dm # of water at $%&' (" dm # ) "*** cm # ) " litre+
What is solubility?
4or e+am le, the sol- ilit! of sodi-m 'hloride is 3)0 %?dm3.
,$+ *hat mass of sodi-m 'hloride wo-ld dissol e in 2 dm 3
of water at 25 @
,#+ *hat mass of sodi-m 'hloride wo-ld dissol e in 500 'm 3 of water at 25 @
,"+ *hat wo-ld ha en if !o- added more than 3)0 % ofsodi-m 'hloride to 1 dm 3 of water
ol- ilit! is defined as/
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-nvestigating solubility
n e+ eriment was 'arried o-t to determine the sol- ilit! of an-m er of solid 'hlorides. Here are the res-lts/
How 'an !o- -se the res-lts to 'al'-late the sol- ilit! in %?dm 3 of ea'h solid
200 'm 3'u'l $
chloride volume ofwater
.g'l $/'l
0a'l
1n'l $
mass of chloridethat dissolved
151 %
80 %30 %
&2 %
)18 %
150 'm 3
100 'm 3
200 'm 3
150 'm3
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'alculating solubility
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Which chloride is the most soluble?
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Solubility and temperature
$he sol- ilit! of a s- stan'e de ends on the tem erat-re ofthe sol ent. $his ta le s-mmarises the effe't of tem erat-reon the sol- ilit! of fo-r different solids/
1)&0
otassi-m 'hloride
temperature
0 @ 20 @ (0 @ )0 @ 80 @
sodi-m 'hloride
sodi-m nitrateotassi-m nitrate
solid:
139 31) )13 10)0
280 3(2 (01 (58 513
35& 359 3)( 3&1 380
&30 8&) 1020 1220 1(80
solubility (g2dm #+
How wo-ld !o- 'arr! o-t this e+ eriment
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Solubility and temperature graph
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Saturation and crystalli3ation
ol-tions e'ome supersaturated when the! 'ontain moresol-te than the! wo-ld normall! e a le to dissol e.
$he sol-te will sta! in sol-tion-ntil a Aseed# 'r!stal is added.$his 'a-ses it to 'r!stalli e o-t ofthe sol-tion er! C-i'kl!.
*hen it does this, it %i es o-theat ener%!.
$his 'an ha en when a sat-ratedsol-tion is 'ooled, or another'han%e in 'onditions o''-rs that
'a-ses sol- ilit! to de'rease.
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Solubility of gases
an! %ases are sol- lein water. 4or e+am le,fish 'an reathe
e'a-se of the o+!%endissol ed in water.
4i ! drinks 'ontain'ar on dio+ide that has
een dissol ed intothem -nder ress-re.
*hen the ress-re inside the 'ontainer is released, the'ar on dio+ide %as 'omes o-t of the sol-tion, rod-'in%fi ! - les.
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Solubility of gases and temperature
*hat ha ens to the sol- ilit! of %ases as the tem erat-rein'reases
'ar on dio+ide 3.35 1.)9 0.&)
nitro%en
temperature
0 @ 20 @ 50 @
o+!%en
gas:
0.029 0.019 0.012
0.0)9 0.0(3 0.02&
solubility (g2dm #+
If !o- lea e a %lass of lemonade for a few da!s, it %oes flat.
If !o- left one %lass of lemonade in the frid%e and anothereside the radiator, whi'h is likel! to %o flat first
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Solubility of o4ygen
s the tem erat-re of water in'reases, the sol- ilit! ofo+!%en de'reases.
$his 'an e a ro lem for fish li in%in ri ers near fa'tories.
In ind-str!, water is often -sed tokee ma'hiner! 'ool. $his rod-'eswarm waste water whi'h then flowso-t into near ! ri ers.
ltho-%h the water is 'lean, it 'anstill affe't aC-ati' animals. $he warmwater 'ontains less of the dissol edo+!%en that fish need to reathe.
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Solubility of o4ygen
team of s'ientists in esti%ated the tem erat-re and le elsof dissol ed o+!%en at different oints alon% a ri er.
6 stream of the fa'tor!/ D$hewater is 'ool and 'lean, with lotsof dissol ed o+!%en, and lent!of small in erte rates and fish.
Fownstream of the fa'tor!/ D$hewater is 'lean, -t warm. *e
fo-nd a few dead fish in the ri er.
*hat 'an e done ! the fa'tor! owners to sol e the ro lem
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'arbon dio4ide and the ocean
ar on dio+ide is er! sol- le in water, and s'ientists elie ethat a o-t a third of the 'ar on dio+ide rod-'ed ! -rnin%fossil f-els dissol es into the o'eans.
'5 $
sedimentation
carbonate organic carbon
circulation
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Solubility of carbon dio4ide
ome s'ientists ha e s-%%estedthat the o'eans 'o-ld a't as aD'ar on dio+ide reser oir toremo e it from the atmos here.
Howe er, if %lo al warmin%
'ontin-es and the o'eans %etwarmer, what will ha en tothe amo-nt of 'ar on dio+idedissol ed in the o'eans
$he %as 'o-ld e -m ed downto the ottom of the o'ean andDstored there.
< 2 is a %reenho-se %as.
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Solubility: true or false?
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What is hard water?
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6sing hard and soft water
oft water forms a lather easil! with soa .
Hard water needs moresoa to form a lather,addin% additional 'ost to'leanin% ro'esses.
How 'o-ld !o- test watersam les to see if the! arehard or soft
$his is e'a-sedissol ed 'hemi'als inthe hard water rea't withsoa to form a s'-m.
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What is hard water?
Hard water 'ontains dissol ed 'al'i-m and ma%nesi-m'om o-nds s-'h as/
ma%nesi-m h!dro%en 'ar onate G % H < 3 2'al'i-m h!dro%en 'ar onate G a H < 3 2ma%nesi-m s-lfate G % < ('al'i-m s-lfate G a < (
Hard water 'an e tem orar! or ermanent.
7ermanent hard water 'ontains ma%nesi-m s-lfate and'al'i-m s-lfate.
Temporary hard water 'ontains ma%nesi-m h!dro%en
'ar onate and 'al'i-m h!dro%en 'ar onate.
d h l
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Hard water chemicals
d d
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Hard water and soap
ainwater e'omes sli%htl! a'idi' as 'ar on dio+ide fromthe air dissol es in it, formin% 'ar oni' a'id.Limestone 'ontains 'al'i-m 'ar onate. s the sli%htl! a'idi'rainwater tri'kles thro-%h ro'ks, the 'al'i-m 'ar onaterea'ts to form sol- le 'al'i-m h!dro%en 'ar onate/
8 8 8carbonicacid
H$'5 # (a9+
calciumcarbonate
'a'5 # (s+
calcium hydrogencarbonate
'a(H'5 #+$ (a9+
carbondio4ide
'5 $ (g+
water
H$5 (l+8 8 8
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How does hard water react with soap?
oa As'-m# is formed ! the rea'tion/
$he soa will onl! form a lather when all the dissol ed'al'i-m h!dro%en 'ar onate in the water has rea'ted.
sodiumstearate
$' " H#%'550a (s+ $0aH'5 # (a9+(' " H#%'55+ $'a (s+
calciumhydrogencarbonate
'a(H'5 #+$ (a9+
8 calciumstearate
sodiumhydrogencarbonate
8
8 8
6sin% hard water 'an 'a-se ro lems/
ore soa is needed to %et a lather.
It 'an e diffi'-lt to 'lean the s'-m from atht- s and sinks.
Hard water 'an e -ns-ita le for ind-strial ro'esseslike d!in%.
i l
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;imescale
*hen hard water is heated, the dissol ed 'al'i-m h!dro%en'ar onate de'om oses to form solid 'al'i-m 'ar onate.
$hese de osits of 'al'i-m 'ar onate are 'alled limescale .
Limes'ale 'an lo'k i es and 'oatthe heatin% elements in kettles,
washin% ma'hines and heaters.
8
8
calcium hydrogencarbonate
'a(H'5 #+$ (a9+
calciumcarbonate
'a'5 # (s+
water
H$5 (l+
carbon dio4ide
'5 $ (g+
8
8
Limes'ale is a oor heat 'ond-'tor, andred-'es the effi'ien'! of a lian'es.
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Wh t th b fit f h d t ?
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What are the benefits of hard water?
Hard water 'an e %ood for health/
'al'i-m is needed for health!ones and teeth
ma%nesi-m is needed for effe'ti emeta olism.
ome st-dies ha e also shown thateo le li in% in hard water areas areless likel! to s-ffer from heart disease.
$he *orld Health
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Softening temporary hard water
$em orar! hard water 'ontains 'al'i-m h!dro%en 'ar onate.
$his is relati el! eas! to remo e, e'a-se it de'om oses onheatin% to form solid 'al'i-m 'ar onate/
7nowin% this, how wo-ld !o- remo e the solid 'al'i-m'ar onate from the water
*hat wo-ld e left ehind after remo in% tem orar!hardness -sin% this method
8
8
calcium hydrogen
carbonate'a(H'5 #+$ (a9+
calcium
carbonate'a'5 # (s+
water
H$5 (l+
carbon dio4ide
'5 $ (g+
8
8
S ft i g h d t
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Softening hard water
Both tem orar! and ermanent hard water 'an e softened! addin% sodi-m 'ar onate washin% soda .
$he sodi-m 'ar onate rea'ts with the 'al'i-m 'om o-nds inthe water to form 'al'i-m 'ar onate and sol- le sodi-m'om o-nds, whi'h do not 'ontri -te to hardness/
8 8calcium
hydrogencarbonate
'a(H'5 #+$ (a9+
sodiumcarbonate
0a $'5 # (s+
calciumcarbonate
'a'5 # (s+
sodiumhydrogencarbonate
$0aH'5 # (a9+8 8
*hat is the word and s!m ol eC-ation for the rea'tionetween 'al'i-m s-lfate whi'h 'a-ses ermanent
hardness and sodi-m 'ar onate
S ft i g h d t
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Softening hard water
Hard water: summary
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Hard water: summary
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What is soap?
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water
oil
soap molecule
What is soap?
If oil is added to water, the two liC-ids do not mi+.
Be'a-se of this, %rease stains 'an e diffi'-lt to remo ed-rin% washin%.
oa s are 'om o-nds
whi'h a't as emulsifiers .
$his means that the!hel the oil to mi+with the water.
How do soaps wor ?
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How do soaps wor ?
How are soaps made?
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How are soaps made?
oa s are -s-all! made from e%eta le fats and oils.$hese 'onsist of 3 fatt! a'id 'hains, held to%ether ! a%l!'erol mole'-le.
$he rea'tion -sed to make soa from fats and oils is'alled saponification .
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What are soapless detergents?
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What are soapless detergents?
oa less deter%ents 'an e made from 'r-de oil, rather thane%eta le oils or animal fats.
sodium octadecylsulfonate
h!dro ho i' end intera'tswith oil mole'-les
h!dro hili' end intera'tswith water mole'-les
oa less deter%ents are still made of lon%, h!dro ho i''ar on 'hains, -t the h!dro hili' end of the mole'-le is as-lfonate/
Soaps vs= soapless detergents
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Soaps vs= soapless detergents
*hat are the ad anta%es and disad anta%es of soa lessdeter%ents o er soa s
oa s form a s'-m with hard water, meanin% that it ismore diffi'-lt to rod-'e a lather. oa less deter%entsrea't with the s- stan'es in hard water to form sol- le'om o-nds, and so do not form a s'-m.
oa less deter%ents 'an e made from the !J rod-'tsof the oil refinin% ro'ess, so 'an e 'hea er to rod-'ethan soa s.
ome soa less deter%ents are not iode%rada le.$his means that the! sta! in the water s!stem 'a-sin%froth in ri ers and streams.
>iological and non biological detergents
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>iological and non biological detergents
Biolo%i'al deter%entsare soa lessdeter%ents that'ontain en !mes.
$he en !mes
are -sed to reakdown 'hemi'als,e.%. in stains on'lothes.
:onJ iolo%i'al deter%ents do not 'ontain en !mes, -t K-strel! on the a'tion of the deter%ent to remo e %rease andstains from items.
@dvantage or disadvantage?
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@dvantage or disadvantage?
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Alossary
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Alossary
@nagrams
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@nagrams
ultiple choice 9ui3
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