posted by James on .
Acetic acid is a polar molecule and can form hydrogen bonds with water molecules. Therefore, it has high solubility in water. Yet acetic acid is also soluble in benzene (C6H6), a nonpolar solvent that lacks the ability to form hydrogen bonds. A solution of 3.8g of CH3COOH in 80g of C6H6 has a freezing point of 3.5 degrees celsius. Calculate the molar mass of the solute and suggest what it's structure might be.
Look up the freezing point of benzene, then delta T = f.p.=3.5 = Kf*m
Solve for molality.
molality = moles/kg solvent
Solve for moles.
moles acetic acid = grams acetic acid/molar mass acetic acid
Solve for molar mass. You would expect to find 60 for the molar mass CH3COOH.
You will also need to look up the Kf for benzene.