Coagulation of Latex

Latex coagulates when acid is added.

Latex coagulates when ethanoic acid is added to it. Explain.

1. Latex is a mixture of rubber particles and water. Rubber particle is made up of  a protein membrane that surrounds many rubber molecules.
2. The negatively charged protein membrane prevent repel each other. Latex does not coagulate.
3. Acid which consists of H⁺ ion is added into the latex.
4. The H⁺ ion from acids neutralize the negatively charged protein membrane.
5. The rubber particles collide with each other.
6. Protein membrane of the rubber particle breaks. 
7. Rubber molecules clump together. Latex coagulates.

When latex is exposed to the air for some time, it still coagulates. Why?

1. Bacteria from the air enter the latex.
2. The growth of bacteria produces lactic acid.
3. Lactic acid causes coagulation of latex. But this process occurs slowly. Why?
4. Slow bacteria action.

How to prevent coagulation of latex? Explain.

1. By adding ammonia solution.
2. Ammonia solution consists of OH- ion that neutralize the acid produced by the bacteria.
3. The rubber particles remain negatively charged.
4. Coagulation of latex is prevented.

5H students are studying coagulation of latex by adding ethanoic acid

Ethanoic acid is added drop by drop into latex in the beaker. The latex is stirred by using glass rod.