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

Answer 1

The correct option is C $0.73M$

Mole of 2.5 L of 1 M $NaOH$ $=2.5\times 1=2.5$

Mole 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 $=2.5+3.0=5.5L$)

Thus, $M_1\times V_1=M_2\times V_2$

$4.0=M_2\times 5.5$

Molarity of resultant solution =$M_2=\frac{4.0}{5.5}$ = $=0.73M$