Question

Which of the following statements are correct regarding the hardness of water?

• A. The temporary hardness of water is due to the presence of bicarbonates of $CaandMg$
• B. The temporary hardness of water is due to the presence of sulphates of $NaandMg.$
• C. The permanent hardness of water is due to the presence of bicarbonates of $NaandMg.$
• D. Permanent hardness is due to presence of soluble chlorides and sulphates of $CaandMg.$

Answer 1

Answer: (A), (D)

The correct options are
A The temporary hardness of water is due to the presence of bicarbonates of $CaandMg$
D Permanent hardness is due to presence of soluble chlorides and sulphates of $CaandMg.$

Types of Hardness :
1. Temporary hardness
2. Permanent hardness
Temporary hardness
Temporary hardness is due to the presence of soluble bicarbonates
of $CaandMg.$
Examples: $Ca\left(HC{O}_3{)}_{2}andMg\right(HC{O}_3{)}_2$
Boiling :
$Mg\left(HC{O}_3{)}_2\right(aq\left)\stackrel{\Delta }{⟶}MgC{O}_3\right(s)+C{O}_2(g)+H_{2}O(l)$
$Ca\left(HC{O}_3{)}_2\right(aq\left)\stackrel{\Delta }{⟶}CaC{O}_3\right(s)+C{O}_2(g)+H_{2}O(l)$
Permanent hardness :
Permanent hardness is due to presence of soluble chlorides and sulphates of Mg and Ca.
Example: $CaC{l}_2,CaS{O}_4,MgC{l}_2,MgS{O}_4$
This type of hardness is referred to as "permanent" because unlike temporary hardness, it cannot be removed by simple methods.