If 0.380 mol of a nonvolatile nonelectrolyte are dissolved in 3.00 mol of water, what is the vapor pressure P(H2O) of the resulting solution? The vapor pressure of pure water is 23.8 torr at 25 C.

I got this answer correct: 21.1 torr

A solution is composed of 1.50mol cyclohexane (Pey=97.6torr) and 2.20 mol acetone (P=229.5torr). What is the total vapor pressure (Ptotal) above this solution?
I got the correct answer: 176 torr

However, I am confused about part B. Can anyone help explain how to do this problem?

As you saw in Part B, the vapor above the cyclohexane-acetone solution is composed of both cyclohexane vapor and acetone vapor. What mole fraction of the vapor above the solution, , is cyclohexane?

i got the mole fraction of cyclohexane in the solution but that isn't what it wants and I don't know exactly what the question is asking for.

Can someone please explain to me how to do this problem?

To find the mole fraction of cyclohexane in the vapor above the solution, you need to calculate the partial pressures of cyclohexane and acetone and then use the following formula:

Mole fraction of cyclohexane (Xcyclohexane) = Partial pressure of cyclohexane (Pcyclohexane) / Total pressure of the mixture (Ptotal)

First, calculate the partial pressures of cyclohexane and acetone:

Partial pressure of cyclohexane (Pcyclohexane) = Mole fraction of cyclohexane (Xcyclohexane) * Total pressure of the mixture (Ptotal)

Partial pressure of acetone (Pacetone) = Mole fraction of acetone (Xacetone) * Total pressure of the mixture (Ptotal)

Next, substitute the values given:

Partial pressure of cyclohexane (Pcyclohexane) = Xcyclohexane * Ptotal
Partial pressure of acetone (Pacetone) = Xacetone * Ptotal

Finally, substitute these values into the mole fraction formula:

Mole fraction of cyclohexane (Xcyclohexane) = Pcyclohexane / Ptotal
Mole fraction of acetone (Xacetone) = Pacetone / Ptotal

To find the mole fraction of cyclohexane, you can rearrange the equation as:

Mole fraction of cyclohexane (Xcyclohexane) = Pcyclohexane / (Pcyclohexane + Pacetone)

Now, substitute the given values:

Mole fraction of cyclohexane (Xcyclohexane) = (97.6 torr) / ((97.6 torr) + (229.5 torr))

Simplify the expression to get the final answer for the mole fraction of cyclohexane.