Question

The molecular weight of an organic compound is 58.0 g/mol. Compute the boiling point of a solution containing 24.0 g of the solute and 600 g of water, when the barometric pressure is such that pure water boils at 99.735${}^o$C. (K${}_b$ for water $={0.513}^{o}C/m$)

• A. 100.089${}^o$C
• B. 102.019${}^o$C
• C. 110.709${}^o$C
• D. 110.013${}^o$C

Answer 1

Answer: (A)

100.089${}^o$C

The expression for the elevation in boiling point and the molar mass of the solute is as shown below.

$\Delta T_b=\frac{1000K_b\times W_2}{M_2\times W_1}$

Substitute values in the above expression.

$\Delta T_b=\frac{1000\times 0.513\times 24}{58\times 600}=0.354$

The boiling point of solution $=0.354+99.735={100.089}^{o}C$