Key Points
Key Points: Cleansing Agents
Cleansing agents are substances used to remove stain, dirt, or clutter from a surface.
Soaps:
- Soaps are sodium or potassium salts of long chain fatty acids
- Obtained by alkaline hydrolysis (saponification) of natural oils and fats with NaOH or KOH
- Reaction: Natural oil/fat + NaOH/KOH → Soap + Glycerol
- Example: Sodium stearate (C₁₇H₃₅COONa)
- Chemically, soaps are triesters of long chain fatty acids and propan-1,2,3-triol (commonly called glycerol or glycerin)
Synthetic Detergents:
Synthetic detergents work in hard water (unlike soaps). Three types:
| Type | Example | Use |
|---|---|---|
| Anionic detergents | (Sodium lauryl sulphate) \[CH_3(CH_2)_{10}CH_2OSO_3^{\oplus}Na^{\oplus}\] | Household detergent, additive in toothpaste |
| Cationic detergents | \[\mathrm{CH_{3}(CH_{2})_{15}-N^{\oplus}(CH_{3})_{3}Br^{\oplus}}\] (Cetyltrimethyl ammonium bromide) | Hair conditioner, germicide |
| Non-ionic detergents |
\[CH_{3}\left(CH_{2}\right)_{16}-COO\left(CH_{2}CH_{2}O\right)_{n}CH_{2}CH_{2}OH\] (an ester) | Liquid dishwash |
 |
liquid detergent |
