Question

what are detergents chemically?list two merits and two demerits of using detergents for cleaning. state the reason for the having calcium and magnesium ions

Answer 1

Detergents is the sodium salt of a long chain Benzene Suplhonic acid which has cleansing properties in water.
A detergent has a large non ionic hydrocarbon group and an ionic group like sulphonate group, SO³⁻ Na⁺.
Examples of detergents are :
Sodium n-dodecyl benzene sulphonate and sodium n-dodecyl sulphate
Cleansing action of detergent is same as soap.
Merits of using Detergent :
 1. detergents can be used even with hard water where as soaps are not suitable for use with hard water.
2. Detergents have stronger cleansing action than soaps.
3. detergents are more soluble in water than soaps.
Demerits of using Detergents:
1. Detergents are not biodegradable that is they cannot be composed by micro organisms like bacteria
2. Detergents causes water pollution .

Reason for the having calcium and magnesium ions :
Detergents react with with Ca²⁺ and Mg²⁺ ions in hard water forming soluble compounds. lather is formed easily and cleansing action is efficient.

Answer 2

A detergent is a surfactant or a combination of surfactants with cleaning properties in a dilute solution. These substances are generally alkylbenzenesulphonates, a family of compounds similar to soap but with better cleaning properties, as they are soluble even in hard water. Major applications of detergents is in the households, laundries, as fuel additives and as biological reagents. In our homes, we use detergents for washing our utensils, dishes and clothes.
As calcium and magnesium salts are present in detergents, they function as dirt removers, as dirt particles cling to them during washing activity. Washing clothes with hard water is eased as these ions help in softening it.
But, these ions also have a tendency of weakening the fabric and affecting the colour of the clothing.