Part A If 0.840 mol of a nonvolatile nonelectrolyte are dissolved in 3.90 mol of
ID: 986730 • Letter: P
Question
Part A
If 0.840 mol of a nonvolatile nonelectrolyte are dissolved in 3.90 mol of water, what is the vapor pressure PH2O of the resulting solution? The vapor pressure of pure water is 23.8 torr at 25 C .
Express your answer with the appropriate units.
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Solutions containing volatile solutes
In solutions composed of two liquids (A and B), each liquid contributes to the total vapor pressure above the solution. The total vapor pressure is the sum of the partial pressures of the components:
Ptotal=PA+PB=XAPA+XBPB
where PA and PB are the vapor pressures of pure A and B, respectively.
Part B
A solution is composed of 1.50 mol cyclohexane (Pcy=97.6 torr) and 2.90 mol acetone (Pac=229.5 torr). What is the total vapor pressure Ptotal above this solution?
Express your answer with the appropriate units.
PH2O =Explanation / Answer
P - P0 / P0 = n1/ n1 + n2
(P - 23.8) = 0.84/ (0.84 + 3.9)
P = 23.977
partial pressure of Pcy = (n1 / (n1+n2)) * P0 cy = (1.5 / (1.5 + 2.9)) *97.6
Pcy = 33.273 torr
partial pressure of Pac = (n2 / (n1+n2)) * P0 ac = (2.9 / (1.5 + 2.9)) *229.5
Pcy = 151.26 torr