

InterviewSolution
Saved Bookmarks
1. |
Why does hard water not form lather with soap ? |
Answer» Hard water contains bicarbonates , chlorides and sulphates of `Ca^(2+)` and `Mg^(2+)` . These combine with soap molecules to form precipiatates of calcium and magnesium salts of soaps. `underset("(Soap)")underset("Sod. Stearate")(2C_(17)H_(35)COONa)+Ca^(+) to underset("(Curdy white ppt.)")underset("Cal. stearate")((C_(17)H_(35)COO)_(2)Ca)+ 2Na^(+)` `underset("(Soap)")underset("Sod. Stearate")(2C_(17)H_(35)COONa)+Mg^(2+) to underset("(Curdy white ppt.)")underset("Mag. stearate")((C_(17)H_(35)COO)_(2)Mg)+2Na^(+)` As a result , soap is wasted and hence hard water does not produce lather with soap. |
|