# Physical Chemistry - vapor pressures

1. Sep 25, 2010

### belltos

1. The problem statement, all variables and given/known data

At what temperature will isopropanol (Tbp = 82.5C) and carbon tetrachloride (Tbp = 76.7C) have the same vapour pressure? For isopropanol and carbon tetrachloride, the standard enthalpies of vaporization are 32.54 kJ mol-1 and 44.0 kJ mol-1, respectively.

2. Relevant equations
Clapeyron Equation???

3. The attempt at a solution
I don't really know how to get started.

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Sep 25, 2010

### Staff: Mentor

You are right about using Clapeyron equation.

What does boiling point mean? How is it related to vapor pressure?

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3. Sep 25, 2010

### belltos

The only relationship I know between boiling point and vapor pressure is that the boiling point is the temperature where the vapor pressure of a liquid is equal to external pressure.

4. Sep 27, 2010

### Staff: Mentor

External pressure is 1 atm - that means you are given p1, T1 and vaporization enthalpy for each substance. That's enough to find any p2/T2 pair.