Question

200 mL of a 1 M $HN{O}_3$ solution is mixed with 300 mL of 6 M $HN{O}_3$ and the final solution is diluted to 1000 mL. Calculate the concentration of $H^{+}$ ions.

• A. 2 M
• B. 1 M
• C. 4 M
• D. 6 M

Answer 1

The correct option is A 2 M

Let $M$ be the molarity of the final solution.
Conserving the total moles before and after mixing:
$M_1{V}_1+M_2{V}_2=MV$
where $M_2$ and $V_2$ are the molarity and volume of 1 M solution.
$M_1$ and $V_1$ are the molarity and volume of 6 M solution.
So,
$(M\times 1000)=(1\times 200)+(6\times 300)$
On solving, molarity = 2 M
Since $HN{O}_3$ dissociates to $H^{+}$ ion and $N{O}_3^{-}$ ion
Concentration of $H^{+}\text{ions}=2M$