Question

Soaps do not work in hard water containing calcium and magnesium ions because

• A. $Ca^{2 +}$and $Mg^{2 +}$ions from insoluble calcium and magnesium salts in the form of scum
• B. $Na^{+}$and $K^{+}$present in soap react with $Ca^{2 +}$and $Mg^{2 +}$and hinder cleansing process
• C. A large amount of soap is to be used in presence of $Ca^{2 +}$and $Mg^{2 +}$
• D. Scum formed by combination of $Na^{+}$, and $Mg^{2 +}$stick to the cloth and are not removed on agitation.

Answer 1

Answer: (A)

$Ca^{2 +}$and $Mg^{2 +}$ions from insoluble calcium and magnesium salts in the form of scum

Answer 2

: $Ca^{2 +}$and $Mg^{2 +}$ ions form insoluble calcium and magnesium soaps respectively when sodium or potassium soaps are dissolved in hard water.

& Inso{lub}lecalcium \\ & Stearate(soap) \end{aligned}}{(C_{17}H_{35}COO)_{2}Ca}$$ These insoluble soaps separate as scum in water and are useless as cleansing agent.