Posted by Anonymous on .
A 4.1 L sealed bottle containing 0.25 g of liquid ethanol, C2H6O, is placed in a refrigerator and reaches equilibrium with its vapor at 11°C. The vapor pressure of ethanol is 10 torr at 2.3°C and 40 torr at 19°C.
(a) What mass of ethanol is present in the vapor?

chem 
DrBob222,
Step 1. Use the ClausiusClapeyron equation to solve for delta Hvap/mol.
Step 2. Knowing delta Hvap/mol for ethanol, calculate vapor pressure of ethanol @ 11 C.
Step 3. Use PV = nRT to solve for n =number of moles of ethanol vapor at 11 C.
Step 4. moles = grams/molar mass
Solve for grams.
Check my thinking. Post your work if you get stuck. 
chem 
123,
how to use the ClausiusClapeyron equation in this question?