Question

1 M and 2.5 litre NaOH solution mixed with another 0.5 M and 3 litre 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 = $M_2 = \frac {4.0}{5.5} M$
$\approx 0.73 \,\, M$