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Science-Related Homework Help Chemistry Topic started by: tole034 on Aug 22, 2012



Title: AP Chemistry problem help! Explain in steps and reasoning?
Post by: tole034 on Aug 22, 2012
The vapor pressure of water at 20 degrees celsius is 17.5 torr. A 20% solution of the nonvolatile solute C2H4(OH)2 (molecular mass 62.0 g/mol), in water is prepared. Estimate the vapor pressure of the solution.

I know that you are supposed to use raoult's law here but could somebody please explain the proper steps and reasonings within the problem and raoult's law in order to derive the answer? Thanks


Title: AP Chemistry problem help! Explain in steps and reasoning?
Post by: toma2004 on Aug 22, 2012
mass C2H4(OH)2 = 20 g
moles C2H4(OH)2 = 20 / 62.0=0.323
mass water = 80 g
moles water = 80 / 18 g/mol=4.44
mole fraction water = 4.44 / 4.44 + 0.323 =0.932
p = 0.932 x 17.5 =16.3 torr