Question

Hardening of leather in tanning industry is based on:
A. Electrophoresis
B. Electro-osmosis
C. Mutual coagulation
D. Persistent dialysis

Answer 1

Hint: In this type of question we have to clearly know about the definition of process required for the special purpose. Like in the tanning industry, hardening of leather is due to the mutual coagulation process.

Complete Step by step answer: Firstly we have to know for the tannin. In the process of tannin two chemicals of opposite charges are coagulated.
As in the given question in the tanning process the negatively charged colloidal chemical is required for the leather because leather is positively charged so we have a chemical of opposite charge to complete coagulation.
When the leather and chemical with negatively charged ions is soaked with leather the coagulation process is started . This is called mutual coagulation .
When positively charged particles and negative colloids mixed up this coagulation leads to the hardening of leather.
So the hardening of leather in the tanning industry is due to mutual coagulation of charges.

Therefore, option number c will be the correct option.

Note: Mutual coagulation is the process of destabilization of colloids by neutralizing electric charge of dispersed phase particles which result in the aggregation of the particle. It should be taken in mind that if it becomes too hard it may lead to brittle failure, so the hardening process should be in optimum condition.