Question

A solution is made by mixing 38.0 mL of ethanol, C2H6O, and 62.0 mL of water. Assuming ideal behavior, what is the vapor pressure of the solution at 20 °C?

Answer 1

You will need density to convert to grams, then convert to mols ethanol and mol H2O.
mol fraction EtOH = XEtOH = nEtOH/total mols
XH2O = nH2O/total mols.

Then pH2O = XH2O*P^o_H2O
pEtOH = XEtOH*P^o<sub>EtOH</sb>
Ptotal = pEtOH + pH2O