Question

The molarity of a solution $M_3$ obtained by mixing these two solutions:
1. $750mL$ of $0.5MHCl$
2 $250mL$ of $2MHCl$
will be:

• A. $1.75M$
• B. $0.975M$
• C. $0.875M$
• D. $1.00M$

Answer 1

The correct option is C $0.875M$

$\text{Millimole of solution I}=M_1\times V_1=750\times 0.5=375mmol$
$\text{Millimole of solution II}=M_2\times V_2=250\times 2=500mmol$

$\text{Total volume}=V_1+V_2=1000mL$
$\therefore M_3=\frac{M_1\times V_1+M_2\times V_2}{V_1+V_2}{M}_3=\frac{375+500}{1000}=0.875M$