Question

Two separate solutions of a non-electrolyte substance are mixed. 480 mL of a 1.5 M solution is mixed with 520 mL of a 1.2 M solution. What is the molarity of the final mixture?

• A. 3.76 M
• B. 5.52 M
• C. 7.13 M
• D. 1.34 M

Answer 1

The correct option is D 1.34 M

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 1.2 M solution.
$M_1$ and $V_1$ are the molarity and volume of 1.5 M solution and $M$ and $V$ are the molarity and volume of the mixture
$(1.5\times 480)+(1.2\times 520)=M\times 1000$
On solving, $M=1.34M$