Question

$1\, M$ and $2.5\,L\,NaOH$ solution mixed with another $0.5\,M$ and $3\,L\,NaOH$ solution. Then find out molarity of resultant solution

• A. 0.80 M
• B. 1.0 M
• C. 0.73 M
• D. 0.50 M

Answer 1

Answer: (C)

0.73 M

Answer 2

Moles of $2.5\, L$ of $1\, M\, NaOH =2.5 \times 1=2.5$ Moles of $3.0\, L$ of $0.5\, M\, NaOH =3.0 \times 0.5=1.5$ Total moles of $NaOH$ in solution $=2.5+1.5=4.0$ (Total volume of solution $=2.5+3.0=5.5 L$ ) Thus $M_{1} \times V_{1}=M_{2} \times V_{2}$ $4.0=M_{2} \times 5.5$ $\therefore$ molarity of resultant solution $=M_{2}=\frac{4.0}{5.5} M$ $\approx 0.73\, M$