Question

The gold number of four protective colloids a, b, c and d are $0.1,0.25,5$and $15$ respectively. the maximum protecting power is of

Answer 1

Gold number of colloids

• The gold number is defined as the minimum amount of protective colloid in mg required to avoid coagulation of $10\text{ml}$ of a particular gold solution when $1\text{ml}$ of a $10\%$ Sodium chloride solution is added to it.
• Because a greater amount of colloid is required to avoid coagulation, the higher the gold number, the lesser the colloid's protective power.

Maximum protecting power

• The value of the gold number is highest for the d colloid.
• So, the protecting power is lowest for d colloid.
• The value of the gold number is the lowest for colloid a.
• So, the protective power is maximum for colloid a.

Hence, the maximum protecting power is of colloid a.