Answer:
The vapor pressure at 298 K for this solution is 50,49 Torr.
Explanation:
We have to apply Raoult's law to solve this which its formula is:
P pure sv° - P sl = P pure sv° . X (molar fraction)
ΔP = P pure sv° . X (molar fraction)
58,9 Torr - P sl = 58,9 Torr . X
Molar mass urea CO(NH2)2: 60,06 g/m
Molar mass ethanol: 46,07 g/m
Moles for urea: 42,4 g / 60,06 g/m = 0,705 moles
Moles for ethanol: 195 g / 46,06 g/m = 4,233 moles
X (molar fraction): moles from solute / moles from solute + moles from solvent
X (molar fraction): 0,705 / 0,705 + 4,233 = 0,142
58,9 Torr - P sl = 58.9 Torr . 0,142
58,9 Torr - 8,40 Torr = P sl
50,49 Torr = P sl
