A solution is made by adding 0.100 mole of ethyl ether to 0.841 mole of ethyl alcohol. If the vapor pressure of ethyl ether and ethyl alcohol at 20oC are 375 torr and 20.0 torr, respectively, the vapor pressure of the solution at 20oC (assuming ideal behavior) is:

Question

A solution is made by adding 0.100 mole of ethyl ether to 0.841 mole of ethyl alcohol. If the vapor pressure of ethyl ether and ethyl alcohol at 20oC are 375 torr and 20.0 torr, respectively, the vapor pressure of the solution at 20oC (assuming ideal behavior) is:
Answer

DrBob222 · Answer

total moles = mol ether + mol EtOH
Xether = moles ether/total mols
XEtOH = moles EtOH/total moles

pether = Xether*Po ether
pEtOH = XEtOH*Po EtOH
Total vapor pressure above the solution = pether + pEtOH.