Question

The mole fraction of the solute in the $12$ molal solution of $N{a}_{2}C{O}_3$ is :

• A. 0.822
• B. 0.177
• C. 1.77
• D. 0.0177

Answer 1

Answer: (B)

0.177

$12$ molal solution means $12$ moles of sodium carbonate in $1$ kg of water.

The number of moles of sodium carbonate, $n_{N{a}_{2}C{O}_3}=12$.

The number of moles of water, $n_{H_{2}O}=\frac{1000}{18}=55.55$.

The mole fraction of sodium carbonate, $X_{N{a}_{2}C{O}_3}=\frac{12}{12+55.55}=0.177$.

Hence, option B is correct.