Question

The molarity of $N{O}_3^{-}$ in the solution after $2L$ of $3M$ $AgN{O}_3$ is mixed with $3L$ of $1M$ $Ba{Cl}_2$ is:

• A. $1.2M$
• B. $1.8M$
• C. $0.5M$
• D. $0.4M$

Answer 1

Answer: (A)

$1.2M$

$2L$ of $3M$ $AgN{O}_3$ will contains $6$ moles of $AgN{O}_3$.
$3L$ of $1M$ $Ba{Cl}_2$ will contain $3$ moles of $Ba{Cl}_2$.
$2AgN{O}_3+Ba{Cl}_2⟶2AgCl+Ba{\left(N{O}_3\right)}_2$
So, $6$ moles of $AgN{O}_3$ will react with $3$ moles on $Ba{Cl}_2$ it means, two solution will react completely to form $3$ moles of $Ba{\left(N{O}_3\right)}_2\equiv 6$ moles of $N{O}_3^{-}$ ions in $2+3=5L$ solution
Hence, molarity of $N{O}_3^{-}=\frac{6}{5}=1.2M$