Question

Calculate the mole fraction of the solution in a solution containing 85g ethanol in 500g of

water

Answer 1

The question requirements is to get the mole fraction of the solution

$\Chi_{solution}=1$

But adjusting the condition of the question to read;

" Calculate the mole fraction of each component of a solution containing $85g$ ethanol in $500g$ of water"

Solution

$\Chi_A=\frac{n_A}{n_A+n_B}$

Where $\Chi_A$ is mole fraction of A

$n_A=$ Moles of A

$n_B=$ Moles of B

$n_{water}=\frac{500}{18}=27.7778$

Molar mass of ethanol $=46g/mol$

$n_{ethanol}=\frac{85}{46}=1.8478$

Total moles $=27.7778+1.8478=29.6256$

$\Chi_{water}=\frac{27.7778}{29.6256}=0.9376$

$\Chi_{ethanol}=\frac{1.8478}{29.6256}=0.0624$