Form 5 Chemistry Bab 5: Consumer and Industrial Chemistry
5.1 Oils and Fats
Oils and fats are esters formed from fatty acids and glycerol (propan-1,2,3-triol); one glycerol reacts with three fatty acid molecules. (p.166)
Oils: from plants, liquid at room temperature, low melting point, high percentage of unsaturated fatty acids (e.g. palm oil). Fats: from animals, solid, high melting point, high percentage of saturated fatty acids (e.g. butter). (p.166)
Saturated fatty acids (palmitic, lauric, stearic) have only single bonds; unsaturated (oleic, linoleic, linolenic) have at least one double bond, lowering the melting point. (p.167)
Hydrogenation converts unsaturated fats to saturated fats using H2 and Ni catalyst, raising the melting point; this is how margarine is made from oil. (p.167)
Uses: biofuel, source of energy and vitamins A, D, E, K, soap and personal care, animal feed. Excess saturated fat raises the risk of arteriosclerosis and obesity. (p.168)
5.2 Cleaning Agents
Soaps are sodium or potassium salts of fatty acids (RCOO−Na+ or RCOO−K+), R having 12–20 carbon atoms. Sodium laurate from coconut oil; sodium palmitate from palm oil. (p.169)
Detergents are non-soap cleaning agents: sodium salts of sulphonic acids (alkyl sulphonate or alkylbenzene sulphonate), made from petroleum fractions. (p.170)
Saponification: hydrolysis of oil or fat by concentrated alkali to give soap and glycerol. Oil/fat + NaOH → soap + glycerol. (p.170)
Detergent preparation: sulphonation (or sulphation of alcohol) with concentrated H2SO4, then neutralisation with NaOH. (p.171)
Soap/detergent anion has a hydrophilic part (soluble in water) and a hydrophobic part (soluble in oil/grease). (p.173)
Cleansing action: surface tension of water is reduced; hydrophobic parts dissolve in grease, hydrophilic parts in water; grease breaks into droplets that repel each other and form an emulsion that is rinsed away. (p.174)
Hard water contains Ca2+ and Mg2+; soap anions form insoluble scum (e.g. calcium stearate), wasting soap. (p.174)
Detergent anions form soluble salts with Ca2+ and Mg2+, so detergents work in hard water. Soap is ineffective in hard and acidic water; detergent is effective in both. (p.175)
Detergent additives: enzymes (remove protein stains), whitening agents, optical whiteners, water softeners/builders (sodium tripolyphosphate), foam control agents, anti-suspension agents, fragrances, drying agents. (p.176)
5.3 Food Additives
Food additives are natural or synthetic ingredients added to prevent spoilage or improve appearance, taste or texture; regulated by the Food Act 1983 and Food Regulations 1985. (p.177)
Additives make food last longer, look better, taste better and allow seasonal food all year, but excess can cause allergies, asthma, hyperactivity, nerve disorders and cancer. (p.179)
5.4 Medicines and Cosmetics
Traditional medicines come from herbal plants or animals, e.g. ginger, ginseng, aloe vera, tamarind. (p.181)
Analgesics (aspirin, paracetamol, codeine) relieve pain; aspirin is acidic and causes stomach ulcers; paracetamol overdose damages the liver; codeine causes drowsiness. (p.182)
Antimicrobials: antibiotics (penicillin, streptomycin) kill bacteria and must be fully consumed; antiseptics (applied externally); disinfectants (non-living objects). (p.182)
Psychotic drugs (haloperidol, chlorpromazine, clozapine) treat psychosis; anti-allergies (antihistamines) cause drowsiness; corticosteroids reduce inflammation, long-term use causes moon face and high blood pressure. (p.183)
Misuse of antibiotics causes resistance; misuse of codeine causes addiction. (p.183)
The Traditional and Complementary Medicine Act 2016 regulates traditional treatments; the NPRA supervises drug safety and cosmetics quality control in Malaysia. (p.184)
Harmful chemicals in cosmetics: mercury (kidney and nervous system damage), hydroquinone, betamethasone valerate, tretinoin; verify products are registered with the NPRA. (p.186)
5.5 Application of Nanotechnology in Industry
Nanoscience is the study of substances at 1–100 nanometres; nanotechnology is the development of substances or gadgets using the properties of nanoparticles. (p.187)
Applications: semiconductors and electronics, energy (long-lasting batteries, solar cells), textiles (water, fire and dirt resistant), agriculture, medicine (drug delivery), food packaging, cosmetics. (p.188)
Graphene is a carbon allotrope (with diamond and graphite): strong and hard, transparent, good conductor of heat and electricity, impermeable, elastic. (p.189)
Graphene was isolated in 2004 by Andre Geim and Konstantin Novoselov (Nobel Prize 2010). (p.189)
5.6 Application of Green Technology in Industrial Waste Management
Green Technology minimises the negative effects of human activities; sectors include energy supply, waste and wastewater management, transportation, agriculture, buildings and industry. (p.191)
The National Green Technology Policy was introduced in 2009; GreenTech Malaysia promotes adoption. (p.191)
Leachate is contaminated liquid from water leached from solid waste. Industrial wastewater may contain heavy metals (arsenic, mercury, lead) that need systematic treatment. (p.192)
Waste management stages: segregation, collection, sorting, then recycling, composting, incineration or landfill (with methane recovery and leachate treatment). (p.192)
Electrocoagulation uses electrolysis with carbon or copper electrodes; pollutants form flocs removed as sludge, which can be used as fertiliser; treated water can be reused or discharged as effluent. (p.193)
Importance of Green Technology: mitigates global warming, more effective waste management, spearheads innovation, improves living standards, cleaner energy. (p.194)