Question

100ml 0.1N HCl is mixed with 100ml of 0.2N NaOH, then the resulting concentration of the solution is:

• A. 0.05 N
• B. 5 N
• C. 2 N
• D. 0.1 N

Answer 1

Answer: (A)

0.05 N

Given Normality of HCI = 0.1 N,

Volume of HCl = 100 ml

Normality of NaOH = 0.2 N,

Volume of NaOH = 100 ml

$\therefore$ Miliequivalents of HCl $=0.1\times 100=10$

$\therefore$ Miliequivalents of NaOH $=0.2\times 200=20$

$HCl+NaOH\to NaCl+H_{2}O$

Miliquivalents before reaction 10 20 0 0

Milliequivalents after reaction 0 10 10 10

No. of moles left in solution = 20 - 10 = 10

Normality of resulting solution $=\frac{\text{No. of moles left in solution}}{\text{Total volume of solution}}$

$=\frac{10}{100+100}=\frac{10}{200}=0.05N$