We need two pieces of information to calculate the reduction of the vapor pressure of the solvent in a solution containing a nonvolatile nonelectrolyte:
The mole fraction of the nonvolatile solute, Xsolute, in the solution. The vapor pressure of the pure solvent, Psolv.
Psoln = Psolvent (1- Xsolute)
Xsolute = (100g /342.3 g/ mol) / ( 100g /342.3 g/ mol) + (250 g/ 18 g/ mol)
X solute = 0.0206
P soln = (23.8 mmHg) (1- 0.0206)
Psoln = 23.31 mmg Hg
Answer:Vapour pressure of the solution =23.31mmHg
Explanation:
Using Raoult's law: Pi = Pi × Xi
To calculate number of moles of H2O = 250g of H2O × 1 / 18g of H20 = 13.9 moles of H2O.
To calculate number of moles of sucrose= 100g of Sucrose × 1/342.3g of sucrose = 0.29moles of Sucrose.
To calculate Vapour pressure,we find:
Mole fraction of water = 13.9 /(13.9 + 0.29) = 13.9/ 14.19 = 0.98
Therefore, the partial pressure of the solution = 0.98 × 23.8= 23.31mmHg
