The calculation of vapor pressure for a solution uses Raoult's law: PA = XA PA°
PA = vapor pressure of the solution
XA = mole fraction of the solvent(a common error is to use the mole fraction of solute)
PA° = vapor pressure of the pure solvent
Thus, as the amount of solute increases, the mole fraction of the solvent decreases as does the vapor pressure of the solution.
First, moles of both substances need to be calculated.
moles = mass / molecular weight
moles of pure H2O = 180.16 g / 18 g/mol = 10.01 moles
moles of C6H12O6= 18.016 g / ((6x12)+ (12x1) + (16x6)) g/mol = 18.016 g/ (72+12+96) g/mol = 18.016 g / 180 g/mol = 0.1 moles
Now, you need to sum moles: 10.01 moles + 0.1 moles = 10.11 moles
X(water) = 10.01 moles / 10.11 moles = 0.990
P (water) = 0.990 x 23.76 mmHg = 23.52 mm Hg
The final answer is d. 23.52 mm Hg
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