5.1 Oils and Fats
Oils and fats are organic compounds classified as esters, produced from the reaction between glycerol (propane-1,2,3-triol) and fatty acids (long-chain carboxylic acids).
Fatty Acid + Glycerol Reaction (Esterification)
$$\text{Glycerol} + 3\text{ Fatty Acids} \rightleftharpoons \text{Fat / Oil (Triglyceride)} + 3\text{H}_2\text{O}$$
Comparison Between Saturated and Unsaturated Fats
- Saturated Fats:
- Derived mainly from animal sources (e.g., butter, lard).
- Contain only single bonds ($\text{C}-\text{C}$) in fatty acid carbon chains.
- Higher melting points, solid at room temperature.
- Unsaturated Fats:
- Derived mainly from plant sources (e.g., palm oil, olive oil, corn oil).
- Contain at least one carbon-carbon double bond ($\text{C}=\text{C}$) in fatty acid carbon chains.
- Lower melting points, liquid at room temperature.
Industrial Conversion: Hydrogenation
Unsaturated liquid oils can be converted into solid saturated fats (e.g., margarine) via hydrogenation. Hydrogen gas ($\text{H}_2$) is reacted with double bonds ($\text{C}=\text{C}$) at $180\text{ }^\circ\text{C}$ in the presence of a nickel catalyst.
5.2 Cleaning Agents: Soaps and Detergents
1. Soaps
Soaps are sodium or potassium salts of fatty acids. Formed via saponification (hydrolysis of oils/fats with concentrated alkalis like $\text{NaOH}$ or $\text{KOH}$).
$$\text{Fat / Oil} + \text{Concentrated Alkali} \rightarrow \text{Soap} + \text{Glycerol}$$
- Example: Sodium palmitate, potassium stearate.
2. Detergents
Detergents are sodium salts of sulfonic acids (synthetic cleaning agents derived from petroleum fractions).
3. Cleansing Action Mechanism
Soap and detergent molecules consist of two distinct parts:
- Hydrophobic tail: Long hydrocarbon chain that is water-repelling and soluble in grease/oil.
- Hydrophilic head: Ionic group (e.g., $-\text{COO}^-\text{Na}^+$ or $-\text{OSO}_3^-\text{Na}^+$) that is water-attracting and soluble in water.
Action: Hydrophobic tails dissolve in grease on fabric; hydrophilic heads remain dissolved in water. Mechanical agitation (scrubbing/rubbing) lifts grease off the surface into small droplets. Electrostatic repulsion between negatively charged hydrophilic heads prevents grease droplets from coagulating, forming an emulsion washed away by water.
4. Comparison in Hard Water
- Hard water contains dissolved calcium ($\text{Ca}^{2+}$) and magnesium ($\text{Mg}^{2+}$) ions.
- Soaps: Form an insoluble precipitate called scum ($\text{Ca/Mg}$ salts of fatty acids), reducing cleaning efficiency and wasting soap.
- Detergents: Form soluble calcium and magnesium salts, so they do not form scum and remain effective in hard water and acidic solutions.
5.3 Food Additives
Food additives are natural or synthetic substances added to food to prevent spoilage, improve appearance, texture, or taste.
| Category | Function | Examples |
|---|
| Preservatives | Prevent micro-organism growth (bacteria/fungi) to prolong shelf life. | Sodium benzoate, salt, sugar, vinegar, sulfur dioxide. |
| Antioxidants | Slow down oxidation of fats/oils to prevent rancidity. | Ascorbic acid (Vitamin C), BHA, BHT, tocopherol (Vitamin E). |
| Flavourings | Enhance taste or restore lost flavor. | Monosodium glutamate (MSG), aspartame, esters (artificial fruit flavors). |
| Stabilisers & Emulsifiers | Mix immiscible liquids (oil & water) and maintain uniform texture. | Lecithin, pectin, gelatin, acacia gum. |
| Thickeners | Thicken liquids to improve food consistency. | Starch, xanthan gum, agar-agar. |
| Dyes / Colourings | Add or restore color to make food visually appealing. | Tartrazine, sunset yellow, caramel. |
5.4 Medicines and Cosmetics
1. Modern Medicines
- Analgesics: Relieve pain without causing loss of consciousness (e.g., Paracetamol, Aspirin, Codeine). Aspirin is acidic and can cause stomach ulceration; Codeine is an addiction-forming narcotic.
- Antimicrobials: Kill or inhibit micro-organism growth.
- Antibiotics (e.g., Penicillin, Streptomycin) — Must complete full prescription course to prevent bacterial resistance.
- Antiseptics (e.g., Iodine, Acriflavine) — Applied to living tissue/wounds.
- Disinfectants (e.g., Chlorine, Phenol) — Used on non-living objects/surfaces.
- Psychotic Drugs: Treat mental illnesses (e.g., Stimulants like Amphetamine; Antidepressants; Antipsychotics).
- Corticosteroids: Reduce inflammation, swelling, and allergic reactions (e.g., Hydrocortisone, Betamethasone).
2. Traditional Medicines
Derived from plants or animals without chemical processing. Examples: Ginger (relieves wind/nausea), Turmeric (antiseptic/anti-inflammatory), Aloe vera (soothes burns), Tongkat Ali (energy tonic), Neem (skin conditions).
3. Cosmetics
- Categories: Makeup cosmetics, Care cosmetics, Fragrances.
- Basic Ingredients: Water, Emulsifiers, Preservatives, Thickening agents, Colourings, Fragrances.
- Hazards: Harmful prohibited chemicals like mercury (causes kidney and nervous system damage), hydroquinone, and tretinoin (cause skin redness and hypersensitivity).
5.5 Application of Nanotechnology in Industry
Nanotechnology involves the development, characterisation, production, and application of structures, devices, and systems by controlling shape and size at the nanometre scale ($1\text{ to }100\text{ nm}$) ($1\text{ nm} = 10^{-9}\text{ m}$).
Graphene
- An allotrope of carbon consisting of a single planar layer of carbon atoms arranged in a 2D hexagonal lattice.
- Physical Properties: Exceptionally strong (tougher than steel), ultra-lightweight, excellent thermal and electrical conductor, transparent, flexible, and impermeable to gases.
- Applications: Flexible touchscreens, high-capacity lithium-ion batteries, solar panels, water desalination membranes, biosensors.
5.6 Application of Green Technology in Industrial Waste Management
Green Technology refers to the development and application of products, equipment, and systems used to conserve the natural environment and resources while minimising negative impacts from human activities.
Industrial Waste Management Strategies
- Wastewater Treatment: Electrocoagulation process using electrolysis to remove suspended solids, heavy metals, and oils from industrial effluent.
- Solid Waste Management: Composting organic waste, recycling industrial plastics/metals, gasification/pyrolysis to convert waste into synthetic fuel.
- Air Pollution Control: Using scrubbers, electrostatic precipitators, and catalytic converters to remove toxic gases ($\text{SO}_2$, $\text{NO}_x$) and soot particles before release into the atmosphere.