1. Rossita Radzak SASER
CHEMICALS FOR CONSUMERS
1. (a) A student washed his socks which had oily stains. Explain the cleansing action of soap on
the oily stains.
 In water soap ionizes to form ions/anion CH3(CH2)x COO- and cation, sodium ions,
Na+
 The anions consists of hydrophilic part ( -COO -) and hydrophobic part (hydrocarbon)
 Hydrophilic part dissolve in water only but hydrophobic part dissolve in grease only
 The anions reduces surface tension of water, causing wetting of greasy surface.
 During washing and scrubbing, the anions pull the grease and lifted it off the surface and
break it into a small droplets (Emulsifying agent)
 Rinsing away the dirty water removes the grease (the dirt) and excess soap and the
surface is clean.
Preparation of soap
Procedure
1. pour 10 cm3 palm oil ( vegetable oil ) into a beaker
2. add 50 cm3 of 5.0 mol dm-3 NaOH / KOH solution
3. heat the mixture for (10 minutes)
4. stir
5. stop heating
6. add 50 cm3 distilled water and solid NaCl
7. boil the mixture for 5 minutes
8. cool
9. filter
10. wash / rinse
11. dry ( press the residue between filter papers
Test
12. place a small amount of the residue into a test tube add distilled water, shake it well.
produce a lot of lather ( very foamy)
Observation : white solid, slippery and produce a lot of lather ( very foamy).
(b) Another student carried out four experiments to investigate the cleansing effect of soap and
detergent on oily stains in soft water and hard water respectively.
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2. Rossita Radzak SASER
Compare the cleansing effect between
(i) Experiments I and II
(ii) Experiment II and IV
Explain the differences in the observation
Exp. I and II
 The oily stain disappears in Experiment I but remains oily in Experiment II.
 Hard water contains Ca2+ and Mg2+ ions which reacts with soap ions to form
scum (insoluble salt)
 The formation of scum makes anions less efficient for cleaning the oily stain on the sock
 In soft water, all anions are used to clean the oily stain
 Thus, soap is only effective as a cleansing agent in soft water and ineffective in hard
water.
Exp. II and IV
 The sock in Experiment II remains oily but is clean in experiment IV.
 The soap anions form scum when reacts with Ca2+ and Mg2+ ions in hard water.
 The formation of scum makes anions less efficient for cleaning
 The detergent anions CH3(CH2)x OSO3- / CH3(CH2)x SO3- do not form a
2+ 2+ O
precipitate with Ca and Mg in hard water.
 Hence, detergent cleans effectively in hard water but soap does not clean effectively in
hard water.
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3. Rossita Radzak SASER
Compare and contrast soap and detergent
Soap Detergent
CH3 (CH2)15 COO- Na+
Sodium carboxylate Sodium alkyl sulphate Sodium alkylbenzene sulphonate
Material : fat, Petroleum fractions : long chain Petroleum fractions : long chain
vegetable oil, NaOH alcohol, NaOH / KOH, alkene, NaOH / KOH,
/ KOH, mol dm-3 5 mol dm-3 , H2SO4 5 mol dm-3, H2SO4
Preparation Preparation Preparation
Saponification 1. sulphonation 1. alkylation
2. neutralization 2. sulphonation
3. neutralization
Food additive
Type Function Examples
Preservatives To slow down/ prevent the Salts/sugar: draws the water out of the cells
growth of microorganism, of microorganism and retards the growth of
therefore food can kept for longer microorganism
periods of time Vinegar: provides an acidic condition that
inhibits the growth of microorganism.
NaNO3 (Burger)
Benzoic acid / sodium benzoate: to slow
down the growth of microorganism
Antioxidants To prevent oxidation that can Ascorbic acid and vitamin E (Tocopherol)
causes rancid fats and brown
fruits
Flavourings To improve the taste of food and Sugar , salt, MSG, vinegar, aspartame and
restore taste loss because of synthetic essences (ester)
processing
Stabilizers To prevent emulsion from Lecithin, fatty acid
separating out.
Thickeners Its use to thicken foods Pectin, acacia gum, gelatine
Dyes To add or restore the colour in Natural dyes and artificial dyes: Azo
food in order to enhance its compounds or triphenyl compound.
visual appeal and match
consumers expectations.
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4. Rossita Radzak SASER
Medicine
Type Function Example Effect on health
Analgesic To relieve pain without Aspirin  -Internal bleeding
affected consciousness and ulceration
-can cause brain and
liver damage to
children
Paracetamol 
Over dose can cause
brain and liver
Codeine  damage
Addiction, depression
and nausea
Antibiotics To treat infections cause by Penicillin,
bacteria (tuberculosis, TB). streptomycin
Can kill or slow down the
growth of bacteria.
Psychotherapeutic To alter the abnormal
thinking, feelings and -High dose can lead
behaviors. Divide into 3 to anxiety,
categories : -amphetamine  hallucinations, severe
a) stimulant: to reduce depression, and
fatigue  psychological
dependence.
b) antidepressant: -barbiturate /
to reduce tension and tranquilizer  Overdose can lead to
anxiety  respiratory
difficulties,
-chlorpromazine  sleeplessness, come,
-haloperidol, death.
c) antipsychotic: to treat  clozapine -dizziness,
psychiatric illness drowsiness, rapid
heartbeat.
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5. Rossita Radzak SASER
The additives in detergent
Type Function Example
Fragrances To add fragrance to both the detergent
and fabrics
Biological enzymes To remove protein stains such as blood Amylases, proteases,
celluloses, lipases
Whitening agents To convert stains into colourless Sodium perborate
substances
Suspension agents To prevent the dirt particles removed Carboxymethylcellulose
from redepositing onto cleaned fabrics (CMC)
Fillers To add to the bulk of the detergent and Sodium sulphate, sodium
enable it to be pour easily silicate
Optical whitening To add brightness and whiteness to Fluorescent dyes
white fabrics.
Builder To enhance the cleaning efficiency of Sodium tripolyphosphate
detergent by softening the water
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