Form 5 Chapter 5.docx

Chemical for Consumers SOAP AND DETERGENT Soap Preparation Process Soaps can be made from animal fats and vegetable oils. Soaps are prepared by hydrolyzing fats or oils under alkaline condition. The reaction is called saponification. This process involves boiling fats or oils with concentrated sodium hydroxide solution or concentrated potassium hydroxide solution to produce glycerol and the salts of fatty acids which are soaps.

General equation for saponifaction

Sodium palmitate (Soap from palmitic acid) 1. The fats or oils are hydrolysed first to form glycerol and fatty acids. The soap produced can be precipitated by adding common salt (sodium chloride) to the reaction mixture. 2. The sodium chloride added reduced the solubility of soap in water. As a result, precipitation of soap occurs. 3. The properties of soap depend on : a) The type of alkali used for saponification b) The type of animal fats or vegetable oils used. 4. Soaps produced from sodium hydroxide are hard, whereas soaps produced from potassium hydroxide are soft. 5. Animal fats (tallow) from cows and vegetable oils (such as palm oil or olive oil) ae used for making soap.

Detergent 1. Detergents are synthetic cleansing agents made from hydrocarbons obtained from petroleum fractions. Thus, detergents are petrochemicals. Detergents are usually sodium salts of sulphuric acid. 2. Detergents can be classified into three main types, depending on the charge on the detergent ion. a) Anionic detergents where the head of the detergent particle contains a negatively charged ion. Negatively Example: R – O – SO3-Na+ (Sodium alkyl sulphate) charged ion b) Cationic detergents where the head of the detergent particle contains a positively charged ion. Positively Example: R – N (CH3)3+BRcharged ion

c) Non ionic detergents Example: R – O – CH2CH2OH

Preparation of detergents 1. The detergent, sodium alkyl sulphate can be prepared from alcohols with chain lengths of 12 to 18 carbon atoms in two steps. Steps 1: Reaction with concentrated sulphuric acid

Step 2: Neutralisation with sodium hydroxide solution.

2. An example of a long chain alcohol is didecan – 1 –ol, CH3(CH2)10CH2OH. The detergent prepared from dodecan -1 –ol is called sodium dodecyl sulphate (IUPAC name) or sodium lauryl sulphate (common name). CH3(CH2)10CH2O-SO3-Na+ .

3. Sodikum alkylbenzene sulphinates, were first used in 1940s. It can be prepared in three steps. The starting materials for making this detergents in a long chain alkene, RCH = CH2 , obtained from the cracking of petroleum.

a) Step 1 : Alkylation

Alkylation is the introduction of the alkyl group to an organic molecule. b) Step 2 : Sulphonation Alkylbenzene produced the react with concentrated sulphuric acid acid to form alkylbenzene sulphonic acid.

Sulphonation is the introduction of the sulphonic acid group, -SO3H to an organic molecule to form sulphonic acid. c) Step 3 : Neutralisation Alkylbenzene sulphonic acid produced reacted with sodium hydroxide to form sodium alkylbenzene sulphonate, the detergent

The cleansing of soap and detergent The following explains the cleansing action of a soap or detergent on a piece of cloth with a greasy stain: a) When soap or detergent is added to water, it reduces the surface tension of water. Therefore, the surface of the cloth is wetted throughout.

b) The hydrophobic part of the soap or detergent anion is soluble in the grease. The hydrophilic part is soluble in water.

c) Mechanical agitation during scrubbing helps to pull the grease free and also break the grease into small droplets

d) The droplets do not coagulate and redeposit on the surface of the cloth due to the repulsion between the negative charges on their surface.

Effectiveness of Cleansing Action of Soap And Detergent. Property

Soap

Cleaning power Ease of rinsing

Less powerfull It is difficult to wash away all soap on clothes. The soap that remains leave and odour and spoils the fabric Slightly alkaline

pH Molecular structure

Determined by the fatty acids found in the oil or fat used to produce soap

Formation of scum

Forms scum with hard water

Detergent More powerfull Rinse out well from clothes

Can be controlled to suit the cleaning task Can be modified to suit the cleaning task. For example, a detergent can be made specially for cleaning toilet bowls. Does not form scum with hard water

Additives in Detergent and Their Function Addictives Biological enzyme Whitening agent

Example Amylases, proteases, cellulases Sodium perborate

Optical whitener

Fluorescent dyes

Builder

Sodium tripolyphosphate

Suspension agent

carboxymethylcellulose

Filler

Sodium sulphate, sodium silicate

Foam control agents

Silicones

Fragrance

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Function To remove protein stains such as blood To convert stains into colourless substances To add brightness and whiteness to white fabrics To enhance the cleaning efficiency of detergent by softening the water To prevent the dirt particles removed from redepositing onto cleaned fabrics. To add to tha bulk of the detergents and enable it to be poured easily To control foaming in detergent To add fragrance to both detergent and fabrics

Food Additives

Uses of food additives  

To make food last longer (to extend the shelf life) To make foods taste better and look better

Effects on health

Types of food additives     

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Preservatives: sodium nitrite, sodium benzoate Antioxidant: ascorbic acid Flavoring: Monosodium glutamate(MSG), aspartame Stabilizer and thickener: gelatin and acacia gum Dye: azo compounds, triphenyl compounds

Allergy: MSG Carcinogenic: NaNO₂ Brain damage Hyperactivity

Functions of food additives     

Preservatives: to inhibit or prevent the growth of moulds, yeast and bacteria that spoil foods Antioxidants: to prevent spoilage of food due to oxidation by oxygen Flavorings agents: to enhance the taste of food Stabilizers and thickeners: to improve the texture of foods Coloring agents: to restore the color or to enhance the natural color

Types of Food Additives and Their Functions. Anti-caking agents – stop ingredients from becoming lumpy. Antioxidants – prevent foods from oxidising, or going rancid. Artificial sweeteners – increase the sweetness. Emulsifiers – stop fats from clotting together. Food acids – maintain the right acid level. Colours – enhance or add colour. Humectants – keep foods moist. Flavours – add flavour. Flavour enhancers – increase the power of a flavour. Foaming agents – maintain uniform aeration of gases in foods. Mineral salts – enhance texture and flavour. Preservatives – stop microbes from multiplying and spoiling the food. Thickeners and vegetable gums – enhance texture and consistency. Stabilisers and firming agents – maintain even food dispersion. Flour treatment – improves baking quality.

A. Preservatives:

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Benzoic acid and benzoates - are found in soft drinks, beer, margarine and acidic foods. They are use to extend shelf life and protect food from fungi and bacteria. Nitrites and nitrates - are found in processed meats, such as sausages, hot dogs, bacon, ham, and luncheon meats, smoked fish. They are used to extend shelf life and protect food from fungi and bacteria; preserve color in meats and dried fruits. Sulfites - are found in dried fruits, shredded coconut, fruit based pie fillings. They are used to extend shelf life and protect food from fungi and bacteria.

B. Antioxidants: Vitamin and minerals is important additive they help to prevent fats from turning rancid and also may protect against cancer, heart disease, and other diseases.

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Ascorbic acid (vitamin C) and ascorbates - are used in fruit products (juices, jams, and canned fruits), acidic foods, and fatty foods. Ascorbates prevent fruit juices from turning brown and fatty foods from becoming rancid. They also improve baking quality in wheat. BHA or BHT - are used to prevent fatty foods from turning rancid when exposed to oxygen. They are added in baked products, cereals, potato chips, and fats and oils. Tocopherols (vitamin E) - are used to prevent rancidity in fats and other damage to food due to exposure to oxygen. They are used in oils and shortenings.

C. Colorings: are used to make food more visually appealing.

Beta carotene, Caramel, Carrot oil, Citrus red # 1, Dehydrated beets, FD&C colors: Blue # 1, 2: Red # 3, 40; Yellow # 5, 6 - used in processed foods, especially sweets and products marketed for children, soft drinks, baked goods, frosting, jams, and margarine.

D. Flavor Enhancers: Improve the flavor of many canned or processed foods.

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Dioctyl sodium-sulfosuccinate - used in processed foods. Disodium granulate - used in canned meats, meat based foods. Hydrolyzed vegetable - used in mixes, stock, processed meats. Monosodium glutamate (MSG) - used in Chinese food, dry mixes, stock cubes, and canned, processed, and frozen meats.

E. Emulsifiers, stabilizers and thickeners:

Carrageenan, Cellulose, Glycerol, Guar gum, Gum Arabic, lecithin, pectins - is used to improve texture and consistency of processed foods by increasing smoothness, creaminess, and volume. Hold in moisture and prevent separation of oil and water. They are found insauces, soups, breads, baked goods, frozen desserts, ice cream, low-fat and artificial cream cheese, condiments, jams, jellies, chocolate, puddings, and milk shakes.

MEDICINE  

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A medicine is a substances used to prevent or cure disease or to reduce pain and suffering due to illness. It can be classified into tradisional medicines and modern medicines. Modern Medicine - Made by scientists in laboratories and are based on substances found in nature Traditional Medicine - Derived from plants and animals. Medicinal Animal Sea cucumber (gamat) Centipede Ant

Plant Aloe vera

Local name

Functions To treat Japanese encephalitis and hole in the heart. To threat lockjaw and convulsion. To treat hepatitis B Uses

Betel

Sireh

Sap used to relieved pain from burns Leaves relieved sore eyes

Bitter gourd

Peria

Fruit used to cure diabetes

Coconut

Kelapa

Garlic

Bawang putih

Ginger

Halia

Ginseng Hibiscus

Ginseng Bunga Raya

Turmeric

Kunyit

Young coconut water reduces fever Reduces infection and hypertension Reduces inflammation and improves blood circulation and digestion Roots maintain good health Leaves relieves headache and hair loss Cures pimples

Lidah buaya

Type of modern medicine

Function

Analgesicsmedicines used to relieve pain without causing numbness of affecting consciousness. Antibiotics-used to kill or slow down the growth of bacteria.

Do not treat the cause of the pain but merely provide enough relief to the patients to allow them to carry out their daily routine. Treat infections caused by bacteria. They will not cure infections caused by viruses. Do not cure mental illness but can reduce many of the symptoms of mental illness.

Psychotherapeutic medicines- used to alter abnormal thinking, feelings or behavior.

Examples Aspirin, paracetamol

Penicillin, streptomycin

Stimulants, antidepressants, antipsychotic