Answer to Question #329679 in General Chemistry for Wen

Question

Calculate the mole fraction of 25% aqueous hydrochloric acid solution

Answer 1

25% solution mean that $\frac{m(HCl)}{m(HCl)+m(H_2O)}=0.25$

Let m(HCl)+m(H₂O)=100 g, then

m(HCl)=25 g

m(H₂O)=100-25=75 g

M(HCl)=1+35.5=36.5 g/mol

M(H₂O)=1x2+16=18 g/mol

n(HCl)=25/36.5=0.68 mol

n(H₂O)=75/18=4.2 mol

$w(HCl)=0.68/4.2=0.162$