Consider two solutions: one formed by adding 10.0 grams of glucose (C6H12O6) to 1.0 L of water

and another formed by adding 10.0 grams of sucrose (C12H22O11) to 1.0 L of water. Which of the

two solutes produces the lower reduction in the vapor pressure of the solvent? Explain fully.

Lowering of vapour pressure of solvent is proportional to number of moles of solute dissolved in it per litre.

No of moles of glucose dissolved

= mass dissolved / molecular weight of glucose

= 10 / 180

=.055 moles.

No of moles of sucrose dissolved = 10 / 342

=.029 moles.

So reduction in vapour pressure will be lower of solution dissolving sucrose. It is so because, no of moles of solute dissolved in it is low.