Question

One litre of a sample of hard water contains 11.1 g $CaC{l}_2$ & $9.5gMgC{l}_2$. Find the concentration of $C{l}^{-}$ ion in the solution.

• A. $0.10M$
• B. $0.05M$
• C. $0.2M$
• D. $0.4M$

Answer 1

The correct option is D $0.4M$

One litre of a sample of hard water contains $11.1$ gm of $CaC{l}_2$.
$11.1$ g $CaC{l}_2$ given $7.1$ g $Cl$ (by calculating the mass percent of $Cl$ in $CaC{l}_2$)

$9.5$ g $MgC{l}_2$ given $7.1$ g $Cl$ (by calculating the mass percent of $Cl$ in $MgC{l}_2$)

Total $Cl=$14.2 g
moles of chlorine $=\frac{14.2}{35.5}=0.4mol$
$\left[C{l}^{-}\right]=\frac{0.4}{1}=0.4M$