What mass of methanol (CH₃OH) whould be required to make one liter of a 0.5 molar solution of methanol in water?

16.0 grams

One liter of a 0.5 molar solution of methanol contains 0.5 moles of methanol. The approximate molecular mass of methanol can be determined by adding the atomic masses of the constituents (1 carbon atom plus 4 hydrogen atoms plus 1 oxgen atom) to get of 32 grams / mole {(1 x 12) + (4 x 1) + (1 x 16)]. Therefore if 1 mole of methanol has a mass of approximately 32 grams, then 0.5 moles of methanol has a mass of 16.0 grams.