Question

Write any two differences between soap and detergent?

Answer 1

Hint: Soap and detergent are derivatives of fatty acid chains in the form of chemical salt. The fatty acid chain belongs to the elements of the s-block group and the p-block group. Detergents are chemically synthesized products which are non-biodegradable in nature.


Complete Solution :
Let us first study what are soaps and detergents.
Soaps: These are material used for the cleansing actions which are naturally obtained from fats and oils like from plants and animals. They act as mild surface-active agents.
- Oils like vegetable oil, olive oil, coconut oil, etc are some from which oils are obtained.
- Since they are made from a natural product, they are eco-friendly and biodegradable.
- These are the slats of mainly sodium and potassium which belong to s-block elements.
- Some examples of soap are sodium stearate, sodium palmitate , etc.
- Soap cannot be used in hard water because it forms scum due to the presence of bicarbonates, chlorides and sulfates of calcium and magnesium in hard water. When the soap reacts with hard water it forms white precipitate. This white precipitate is called scum. The reaction is:
$C{{a}^{2+}}+2RCOON\to \underset{white\text{ }ppt}{\mathop{{{(RCOO)}_{2}}}}\,2N{{a}^{+}}$
Detergents: These are those materials that are used for the cleansing action that combines with oils, dirt, and impurities which make them more soluble in water.
- They are strong surface-active agents. They are alkyl benzene sulphonates.
- They are not obtained from natural products, instead they are produced chemically.
- Since they are produced chemically they are less biodegradable because of the presence of sulfonate groups which do not get easily detached by the micro-organism in the sewage.
- These are ammonium or sulphonate salts with long-chain carboxylic acids.
- Detergents react with both soft water and hard water, hence it does not form scum with water.
Some examples of detergent are sodium lauryl sulfate and deoxycholic acid, etc.

Difference:

Soap	Detergent
The quality of cleansing action of the soap is lesser than the detergents.	The quality of cleansing action of detergent is higher than the soap
The reactivity of soap is less due to which they do not dissolve in hard water. Because hard water contains ions of calcium and magnesium. They form scum with hard water.$C{{a}^{2+}}+2RCOON\to \underset{white\text{ }ppt}{\mathop{{{(RCOO)}_{2}}}}\,2N{{a}^{+}}$	The reactivity of detergent is then that's why they easily dissolve in soft as well as in hard water. They do not form scum with water.

Note: Since both of them are used for cleaning, soaps can be used on our body because it is produced from natural products but detergent cannot be used on humans because they have high chemical content. Due to the high chemical content they can cause skin irritation, they can even be carcinogenic.