Question

50 grams of acetic acid C2H4O2 are dissolved in 200 g of water. Calculate the weight % and mole fraction of the acetic acid in the solution

Answer 1

$50g$   $of$   $C_2H_4O_2$   $in$   $200g$    $H_2O$

so:

$\frac{50}{200+50}+100\%= \frac{50*100}{250}\%=20\%$

$MW of acid = 2*C+4*H+2*O = 2*12+4*1+2*16=$

$=24+4+32=60g/mol$

so:

$\frac{50g}{60g/mol}\approx0.83moles$

it means that

in $50g$ of acid there is $\approx0.83$moles of acid

$MW of H_2O = 2*H+O=2*1+16=2+16=18g/mol$

so:

$\frac{200g}{18g/mol}\approx11.11moles$

it means that:

in $200g$ of water there is $\approx11.11$moles of water

therefore:

$\frac{0.83mol}{11.11mol+0.83mol}= \frac{0.83mol}{11.94mol}=0.069$

So your answers are:

$20\%$

and the mole fraction is:

$0.069$