Chapter 21, Problem 10P

Interpretation Introduction

Interpretation

The working of soap in hard water should be explained.

Concept introduction

Soaps are sodium or potassium salt of long chain fatty acids, produced by a process called saponification. The saponification process is one where a triglyceride and sodium or potassium hydroxide reacts to give glycerol and salt of fatty acid salt (soap). The triglycerides used in the process are mainly obtained from animal fats or vegetable oils.
Soap molecule has both a polar head group and long chain non-polar hydrocarbon tail of fatty acid. The polar head is hydrophilic in nature and the non-polar tail part is hydrophobic in nature and attracts to oil or grease. This causes the dirt particles to detach from the fibers of the cloth. Although soap is a good cleaning agent, its cleaning capacity drastically reduced when used in water which is relatively hard.