# Chem

A solution is made by mixing 50.0 g C3H6O and 50.0 g of CH3OH. What is the vapor pressure of this solution at 25 degrees C? What is the composition of the vapor expressed as a mole fraction? Assume ideal solution and gas behavior. (At 25 degrees C the vapor pressures of pure acetone and methanol are 271 torr and 143 torr, respectively.)

I calculated the vapor pressure [work shown at end] but I'm confused about the second part of the question. What does it mean to find the composition of the vapor expressed as a mole fraction? It can't be just the mole fraction of 50.0 g C3H6O to 50.0 g CH3OH can it?

Work:
P1= X1 * P*1
50.0 g C3H6O x 1 m/58.09g= .8607 m
50.0 g CH3OH x 1 m/32.05g= 1.560 m
.8607 m C3H6O/2.420 m total= .3556
P1= .3556*143 torr= 50.85 torr

I believe you have used Raoult's Law for a non-volatile solute dissolved in a volatile solvent. In this problem, however, BOTH liquids are volatile and what you have used is not appropriate (although some of the calculation is).
Calculate the mole fraction of acetone (which you have done) and the mole fraction of methanol (which you have done).
Then Pacetone=XacetonePoacetone

Pmethanol=XmethanolPomethanol

The total pressure, then, is
Ptotal=Pacetone + Pmethanol

Let me look to see that all of this copied correctly and I will post the second part of the problem separately.
Check my thinking.

To do the second part, one must realize that the VAPOR will be richer in the more volatile component. The problem is asking you to calculate the mole fractions of the components in the vapor. mole fraction of a component = ratio of partial pressure of component/total pressure. You have just calcualted the total P and you have the partial pressures of each component.

Xaceton=Pacetone/Ptotal

Xmethanol=Pmethanol/Ptotal

Check my thinking.

1. 👍 0
2. 👎 0
3. 👁 1,159

## Similar Questions

1. ### chem

In a solution prepared by mixing CH3OH with H2O the major species pesent are 1. a. CH3+, OH, and H2O 2. b. CH3O, H+, and H2O 3. c. CH3OH and H2O 4. d. CH3OH, H+, and OH I know i have to get an equation having trouble doing that!!

2. ### Chemistry

How many CO2 molecules would be formed from the reaction mixture that produces the greatest amount of products? 2CH3OH(g)+3O2(g)--->2CO2(g)+4H2O(g) 3-CH3OH & 3-O2 or 1-CH3OH & 6-O2 or 4-CH3OH & 2-O2

3. ### Chemistry II

Acetone, C3H6O, is the main ingredient of nail polish remover. A solution is made up by adding 35.0mL of acetone(d=0.790g/mL) to 50.0mL of ethyl alcohol,C2H6O(d=0.798 g/mL). Assume that the volumes are additive. From this

4. ### ap chemistry

Rank the compounds CH3OH CH3CH2OH CH3CH2CH2OH in terms of increasing evaporation rate. 1. CH3CH2CH2OH < CH3OH < CH3CH2OH 2. CH3OH < CH3CH2CH2OH < CH3CH2OH 3. CH3OH < CH3CH2OH < CH3CH2CH2OH 4. CH3CH2OH < CH3CH2CH2OH < CH3OH 5.

1. ### Chemistry

A solution is made by mixing 12.0 g of NaOH and 75.0 ml of 0.200 M HNO3 a) write a balanced equation for the reaction that occurs between the solutes. b) Caclulate the concentration of each ion remaining in solution. c) Is the

2. ### chem

Once made by heating wood in the absence of air, methanol (CH3OH) is now made by reacting carbon monoxide and hydrogen at high pressure: CO(g)+2H2(g)→CH3OH(l) How many grams of CH3OH can be made from 40.0g of CO if it all

3. ### physics

an antifreeze solution is made by mixing ethylene glycol (density= 1116 kg/m^3) with water. suppose that the specific gravity of such a solution is 1.0730. assuming that the total volume of the solution is the sum of its parts,

4. ### chemistry

The density of acetonitrile, CH3CN, is 0.786 g/mL, and the density of methanol, CH3OH, is 0.791 g/mL. A solution is made by dissolving 15.0 g of methanol in 250.0 mL of acetonitrile. Assuming that the volumes of the solute and

1. ### chemistry

How many grams of water would you add to 1.00 kg of 1.48 m CH3OH(aq) to reduce the molality to 1.00 m CH3OH. Use two sig figs. I get 4.8 * 10^2 grams and its not right. I want to put this up here again to see if there are any

2. ### Chemistry

Calculate the potential of a silver electrode in contact with the following: (a) a solution that is 0.0150 M in I2 and saturated with AgI. (b) a solution that is 0.0040 M in CN- and 0.0600 Min Ag(CN)2- (c) the solution that

3. ### Math

Calculate the morality of a solution made by mixing 250ml of 0.75M H2SO4 with 400ml of 2.5MH2SO4

4. ### chemistry

C3H6O + 4O2 --> 3CO2(g) + 3H2O(g) deltaH= -1790kJ the density of C3H6O is 0.79g/mL. HOw much heat is released by the combustion of 150mL of acetone?