Question

What is the mole fraction of potassium dichromate, K2Cr2O7, in a solution prepared from 24.42 g of potassium dichromate and 240. g of water? Report your answer in scientific notation with three significant figures

Answer 1

Answer:

$6.19\times 10^{-3}$ is the mole fraction of potassium dichromate.

Explanation:

Mass of potassium dichromate = 24.42 g

Moles of  potassium dichromate =$n_1=\frac{24.42 g}{294.185 g/mol}=0.0830 mol$

Mass of water = 240.0 g

Moles of water =$n_2=\frac{240.0 g}{18.015 g/mol}=13.3222 mol$

Mole fraction is calculated by:

$\chi_1=\frac{n_1}{n_1+n_2}$

$\chi_1=\frac{0.0830 mol}{0.0830 mol+13.3222 mol}=0.00619=6.19\times 10^{-3}$

$6.19\times 10^{-3}$ is the mole fraction of potassium dichromate.