Achemist wishes to decrease the vapor pressure of a large volume of water. which amount of solute will decrease it the most? (note: assume each sample of solute completely dissolves in the water.) a)0.10 mol al2(so4)3 b)0.10 mol sucrose c)0.40 mol glucose d)0.20 mol nacl

A) 0.10 mol

Explanation:

As the relative lowering of vapor pressure is directly proportional to the amount of dissolved solute.

The formula for relative lowering of vapor pressure will be,

where,

= relative lowering in vapor pressure

i = Van'T Hoff factor  

= mole fraction of solute

1. For 0.10 mol

, i= 5 as it is a electrolyte and dissociate to give 5 ions. and concentration of ions will be

2.  For 0.10 mol sucrose

, i= 1 as it is a non electrolyte and does not dissociate, concentration of ions will be

3. For 0.40 mol glucose

, i= 1 as it is a non electrolyte and does not dissociate,  concentration of ions will be

4. For 0.2

, i= 2 as it is a electrolyte and dissociate to give 2 ions, concentration of ions will be

Thus as concentration of solute is highest for , the vapor pressure will be lowest.