Question

A solution is 25% water, 25% ethanol and 50% acetic acid by mass. Calculate the mole fraction of each component.

Answer 1

Let the mass of solution is $100g$

Then, mass of $H_{2}O=25g$

mass of ethanol $=25g$

mass of acetic acid $=50g$

Number of moles of water $=\frac{25g}{18g/mol}=1.4$

Number of moles of ethanol $=\frac{25g}{46g/mol}=0.54$

Number of moles of Acetic acid $=\frac{50g}{60g/mol}=0.8$

Total number of moles $=(1.4+0.54+0.8)=2.74$

Now, mole fraction of water $=\frac{1.4}{2.74}=0.51$

mole fraction of Ethanol $=\frac{0.54}{2.74}=0.197$

mole fraction of acetic acid $=\frac{0.8}{2.74}=0.291$