A solution containing 1.2 g nonvolatile solute in 100 g. of a solvent has a boiling point elevation 1.2 K. Calculate the molar mass of solute if molal elevation constant of solvent is 6.5\ K kg mol^ -1 .

Question

Quantrex Academy · Accepted Answer

Correct answer: B. 65\ g mol^ -1

The elevation in boiling point is given by the formula:

\Delta T_b = K_b \times m

where

m

is the molality of the solution, which can be written as:

m = \dfrac{w_2 \times 1000}{M_2 \times w_1}

Substituting the given values

w_2 = 1.2\ \text{g}

,

w_1 = 100\ \text{g}

,

\Delta T_b = 1.2\ \text{K}

, and

K_b = 6.5\ \text{K kg mol}^{-1}

:

1.2 = 6.5 \times \dfrac{1.2 \times 1000}{M_2 \times 100}

1.2 = 6.5 \times \dfrac{12}{M_2}

M_2 = \dfrac{6.5 \times 12}{1.2}

M_2 = 65\ \text{g mol}^{-1}

Answer:

65\ \text{g mol}^{-1}

A solution containing 1.2 g nonvolatile solute in 100 g. of a...

Options

Correct answer

Step-by-step solution

More from Solutions