NTA Abhyas JEE Main2020Chemistrys Block ElementsPractice
Soaps do not work in hard water containing calcium and magnesium ions because
Options
- AC a 2 + and M g 2 + ions form insoluble calcium and magnesium salts in the form of scum
- BN a + and K + present in soap react with C a 2 + and M g + and hinder cleansing process
- Ca large amount of soap is to be used in presence of C a + and M g +
- Dscum formed by combination of N a + , C a 2 + and M g 2 + stick to the cloth and are not removed on agitation
Correct answer
A. C a 2 + and M g 2 + ions form insoluble calcium and magnesium salts in the form of scum
Step-by-step solution
C a 2 + and M g 2 + ions form insoluble calcium and magnesium soaps respectively when sodium or potassium soaps are dissolved in hard water. 2 C 17 H 35 C O O N a s o a p + C a C l 2 → 2 N a C l + ( C 17 H 35 C O O ) 2 C a Insoluble calcium stearate soap These insoluble soaps separate as scum in water and are useless as cleansing agent.