Soap
- Soap = sodium salts (RCOO-Na+) / potassium salts (RCOO-K+) of long-chain fatty acids
- Alkalis react with fatty acids –> soap
- Fatty acids = animal fats or vegetable oils
- Soap preparation: hydrolysing fats or oils under alkaline condition
- Saponification – alkaline hydrolysis
- Saponification process – boiling fats / oils with concentrated sodium hydroxide solution or concentrated potassium hydroxide solution to produce glycerol + salts of fatty acids (soap)
- Saponification steps: 1. Hydrolysis of fats / oils –> glycerol + fatty acids. 2. Neutralisation of fatty acids + concentrated alkali –> soap + water
- Overall equation: Fats / oils + alkali –> glycerol + soap
- Sodium chloride – reduces the solubility of soap in water
Liquid soap | Solid soap |
Sodium hydroxide + saturated oils (coconut oil) | Potassium hydroxide + unsaturated oil (sunflower oil / olive oil) |
Uses: bathing purposes | Uses: shaving cream |
Detergent
- Detergent = sodium salt of sulphonic acid
- Alkalis react with sulphonic acid –> detergent
- Common detergent: sodium alkyl sulphate & sodium alkylbenzene sulphonate.
- Detergent preparation: 2 processes – 1. Sulphonation. 2. Neutralisation.
- Sulphonation: Petroleum fraction (long chain hydrocarbon compounds) converted into sulphonic acid with the present of concentration sulphuric acid. Water molecule is removed.
- Neutralisation: sulphonic acid neutralised with sodium hydroxide to form detergent (water molecule is formed).
- Other type of detergents: 1. Anionic detergent (dishwashing liquid detergent). 2. Cationic detergent (hair conditioner). 3. Non-ionic detergent (car washing detergent).
Cleansing action of soap and detergent
- Soap and detergent are surfactants. Surfactants are organic compounds that lower the surface tension of a liquid.
- Surfactants act as emulsifiers and foaming agents.
- Anion soap consists of carboxylate ion (hydrophilic = soluble in water) and long hydrocarbon tail (hydrophobic = soluble in grease /oils).
- Anion detergent consists of sulphate ion / sulphonate ion (hydrophilic = soluable in water) and long hydrocarbon tail (hydrophobic = soluble in grease / oils).
The action process
- Soap or detergent is added to water.
- This has lower the surface tension of water and increases the wetting ability of water.
- Hydrophilic part of the anion dissolves in water.
- Hydrophobic part dissolves in grease.
- Scrubbing helps to pull the grease free and break the grease into small droplets.
- These droplets do not coagulate and redeposit on the surface of the cloth. It is because therepulsion between negative charges on the surface.
- The droplets are suspended in water forming an emulsion.
- Foam produces to float the emulsion.
- Rinsing helps to remove these droplets.
The effectiveness of the cleansing action of soap and detergent
Condition | Soap | Detergent |
Hard water (contain calcium & magnesium ion) | Form an insoluble precipitate = soap scum (formation of soap scum causes wastage of soap) | Detergent is effective cleaner. Form soluble substances = calcium or magnesium salts (do not form scum) |
Soft water (do not contain calcium & magnesium ion) | Soap is effective cleaner. | Detergent is effective cleaner. |
Acidic water (contain hydrogen ion) | Form insoluble long-chain fatty acids (reduces the amount of soap used for cleaning) | Detergent is effective cleaner. Form soluble substances (Do not form scum) |
Environment | Soap is biodegradable | Soap is non-biodegradable |
Additives in detergent
Additives | Function | Example |
Biological enzyme | Remove protein stains | Amylase, lipase & protease |
Foam control agent | Control foaming in detergent | Silicones |
Builder | Enhance the surfactant efficiency | Sodium phosphate |
Filler | Make the solid detergent dry and enable the liquid detergent to be poured easily | Sodium silicate |
Fragrance | Add fragrance | - |
Optical brightener | Add brightness by convert UV radiation to blue light and whiteness | Fluorescent dye |
Stabilising agent | Lower the production of foam | Silicones |
Suspension agent | Prevent the dirt particles removed from redepositing onto cleaned fabrics | Sodium carboxymethylcellulose |
Whitening agent | Bleach stains | Sodium hypochlorite |
Food Additives
Food additive = a natural / synthetic substance that is added to food to
- prevent spoilage
- extend food storage life
- improve food appearance
- improve food taste
- improve food texture
A. Preservatives
Function:
- slow down / prevent the growth of microorganisms / bacteria / fungi
- extend food storage life
Example:
Preservatives | Functions | Example | Side effect |
Salt | Draws the water out of the cells of microorganisms. Retards the growth of microorganisms. | Salted vegetables | Increase the risk of cardiovascular diseases |
Sugar | Draws the water out of the cells of microorganisms. Retards the growth of microorganisms. | Fruit jam | Tooth decay, diabetes and obesity |
Vinegar | Inhibits the growth of microorganisms. | Pickled cucumber | |
Sodium nitrite / sodium nitrate | Slows down the growth of microorganisms. Stabilise red colour in meats. | Sausage | Carcinogenic |
Benzoic acid / sodium benzoate | Slows down the growth of microorganisms. | Tomato sauce | |
Sulphur dioxide | Slows down the growth of microorganisms. | Grape juice | Asthma and allergies |
Alternative ways: freezing and refrigeration
Food Additives
B. Antioxidant
Function:
- prevent oxidation (causes rancid fats and brown fruits)
Examples:
Antioxidant | Functions | Example | Side effect |
Vitamin E | Prevent oils from turns rancid | Palm oil & sunflower oil | No |
Vitamin C | Preserve the colour of fruit juice and the formation of nitrosamines | Fruit juice & cured meat | No |
Sodium citrate | Stop rancidity in fats | Ice-cream | - |
BHA (Butylated hydroxyanisole) BHT (Butylated hydroxytoluene) | Retard rancidity in fats, oils and oil-containing foods | Margarine & cereal | Carcinogenic |
Food Additives
C. Flavouring
Functions:
- improve the taste
- improve the smell
- restore taste loss due to food process
Examples:
Flavouring | Functions | Example | Side effect |
MSG (monosodium glutamate) | Bring out the flavor | Salad dressing & canned soup | Headache, thirsty, nausea & chest pain. |
Aspartame (non-sugar sweetener) | Sweeten food (about 180 – 200 times than sugar) | Soft drinks & diet drinks | Increase the risk of leukaemia, cancer and neurological problems |
Synthetic essences (esters) | Produce artificial flavours = natural flavour. Cheaper to use than the real fruits | Methyl butanoate (apple flavour) & octyl ethanoate (orange flavour) | - |
Food Additives
D. Stabilisers
Functions:
- prevent an emulsion from separating out
Example:
Stabilisers | Functions | Example |
Monoglycerides of fatty acids | Mix oil and water | Ice-cream, chewing gum, beverages, whipped topping and margarine |
Acacia gum | Mix two liquids that do not mix together. Forms an emulsion. | Marshmallow, gumdrop, edible glitter, carbonated drink syrup & gummy candies |
Lecithin | Reduces viscosity. Replaces more expensive ingredients. Controls sugar crystallisation and the flow properties of chocolate. Helps in the homogeneous mixing of ingredients. Uses as a coating. | Margarine, dough, candy bar & cocoa powder |
Gelatin | Mixture of peptides and proteins of collagen extracted from the boiled bones, connective tissues, organs and some intestines of animals | Fruit jam, jelly babies, shells of pharmaceutical capsules, margarine & yogurt |
Food Additives
E. Thickeners
Functions:
- thicken food
- give the food dense, smooth and uniform texture
Examples:
Thickeners | Functions | Example | Side effect |
Acacia gum | Reduces the surface tension of liquid. Leads to increased fizzing. Mix two liquids that do not mix together. Forms an emulsion. | Marshmallow, gumdrop, edible glitter, carbonated drink syrup & gummy candies | - |
Gelatin | Mixture of peptides and proteins of collagen extracted from the boiled bones, connective tissues, organs and some intestines of animals | Fruit jam, jelly babies, shells of pharmaceutical capsules, margarine & yogurt | - |
Pectin | Dietary fiber | Fruit jam | - |
Starch | Thicken food | Soup, custard, pudding, noodles and pasta | - |
Modified starch | Increase their visco-stability | Instant soups & cheese sauce granules | - |
Xanthan gum | Helps to prevent oil separation. Increase in the viscosity of a liquid | Sauce & salad dressing | Allergies |
Food Additives
F. Dyes or Colourings
Functions:
- add colour vanished during food processing
- replace colour vanished during food processing
- make food appear more attractive
Examples:
Dyes / Colourings | Function | Examples | Side effect |
Tartrazine E102 / Sunset yellow E110 (artificial dye) | Yellow azo dye | Orange drinks, sweet & custard powder | Hyperactive in children |
Brilliant blue FCF Blue 1 (artificial dye) | Blue triphenyl dye | Ice-cream, beverages, jellies & blue raspberries flavoured product. | Allergic |
Carmosine E122/ Azorubine (artificial dye) | Red azo dye | Sweet, jellies & confections | Carcinogenic & allergic |
Anthocyanin (natural dye – red grape, red cabbages, sweet potatoes and tomatoes) | Natural red colouring | Ice-cream & sweet | - |
Carotenoids / saffron (natural dye – carrots, sweet potatoes and palm oil) | Natural red colouring | Cooking oil & confections | - |
Paprika | Natural red colouring | Dessert food | - |
Butterfly pea (clitoria ternatea) | A blue food dye | Dessert food & confections | - |
Pandan (pandanus amaryllifolius) | A green food dye | Noodles & confections | - |
Medicines
A. Traditional medicine
Source: living thing – animals, plants & minerals
Source | Characteristics | Uses |
Garlic | To treat colds and asthma, lowers the blood pressure, antibiotics | Eaten raw or cooked |
Cocaine | Anaesthetic | Drug is processed from the leave |
Ginseng | Strengthen the body | Boiled with water to produce juice |
Quinine | Treat malaria | Produced from the bark |
Ginger | Treat stomach ache, treat diarrhea, prevent flu | Boiled with water to produce juice |
Peppermint | Increase the body metabolism, treat nausea, indigestion and flu, to treat headaches, muscles and nerve pain | Boiled with water to produce juice or taken in capsule |
Eurycoma longifolia(Tongkat Ali) | Treat wounds, relieve headaches, to lower the body temperature, increase male virility | Dried and boiled with water to produce juice, served as a hot drink / beverage or made into tablets / capsules |
Tamarind (Asam Jawa) | Reduce malaria fever, reduce cough, medicine for gastric problem | Dried and served as a cold drink |
Lemon grass (Serai) | Mosquito repellent, treat cough, headaches and stomach aches | Made into juice |
Centella asiatica (Daun pegaga) | Help maintain youthfulness, relieve hypertension, aid wound healing | Eaten raw or made into juice |
Green tea | Prevent breast, stomach and skin cancers, improve mental alertness, lower the cholesterol levels | Drink as beverage |
Aloe vera (Lidah buaya) | Heal wounds and skin disease, laxative, treat diabetes, osteoarthritis and sunburn | Eaten cooked or leaves produce juice and rub on body |
Medicines
B. Modern medicine
Source: synthesised by scientists
I. Analgesics
Common analgesics | Uses | Side effect |
Aspirin (acetylsalicylic acid) (cannot be given to pregnant mother and children) | Relieve pain, reduce inflammation, reduce ability of blood to clot | Stomach (internal) bleeding, kidney damage, ulceration |
Paracetamol (can be given to children) | Relieve mild to moderate pain, does not irritate stomach or cause internal bleeding | Skin rashes, blood disorders, acute inflammation of the pancreas, liver damage (overdose) |
Codeine (synthesised from morphine / opium) | Relieve headache and used in cough medicines | Drowsiness, irregular heartbeat, hallucination, lead addiction, depression and nausea |