Question

Hydrochloric acid solutions A and B have concentration of $0.5N$ and $0.1N$ respectively. The volume of solutions A and B required to make $2L$ of $0.2N$ hydrochloric are:

• A. $0.5LofA+1.5LofB$
• B. $1.0LofA+1.0LofB$
• C. $1.5LofA+0.5LofB$
• D. $0.75LofA+1.25LofB$

Answer 1

The correct option is A $0.5LofA+1.5LofB$

Two solutions of different normalities are mixed to give $0.2N$ resultant solution.

Thus, formula used is: $N_{resultant}=\frac{N_1{V}_1+N_2{V}_2}{V_1+V_2}$

where, $N_{resultant}=0.2Nand{V}_1+V_2=2L$

$N_1\left(NormalityofAsolution\right)=0.5N$

$N_2\left(NormalityofBsolution\right)=0.1N$

Since final volume of solution of $A$ and $B$ is $2L,$

Thus, if $V_1$ (Volume of solution A) $=x,$

Then, $V_2$ (Volume of solution B) $=2-x$

Therefore,

$0.2=\frac{(0.5\times x)+0.1(2-x)}{x+2-x}$

$0.2=\frac{0.5x+0.2-0.1x}{2}$

$0.4=0.4x+0.2$

$\Rightarrow 0.4x=0.4-0.2$

$x=\frac{0.2}{0.4}=0.5L$

And $2-x=1.5L$

Thus, volume of solution $A$ and $B$ required is $0.5L$ and $1.5L$ respectively.

So, option (c) is the correct answer.