The vapor pressure of chloroform is 173.11 mm Hg at 25 degrees celsius. A nonvolatile, nonelectrolyte that dissolves in chloroform is aspirin. Calculate the vapor pressure of the solution at 25 degrees celsius when 6.243g of aspirin (180.1g/mol) are dissolved in 244.5g of chloroform.

Chloroform=119.40

I did 6.243g aspirin / 180.1g = 0.0346 moles

244.5g / 119.40g = 2.04 moles

Yes im sorry I am sort of confused. So is the total number of moles what they gave me in the problem, 6.243?

No. They didn't give you that in the problem. How can 6.243 g be 6.243 moles. A mole is a mole. A gram is a gram.

This is basic stuff. You must have calculated moles a million times by now. mols = grams/molar mass.

The vapor pressure of liquid chloroform, CHCl3, is 400.0 torr at 24.1°C and 100.0 torr at -6.3°C. What is ΔHvap of chloroform?

No problem! Let me explain it to you step by step.

To find the vapor pressure of the solution, we need to apply Raoult's law. According to Raoult's law, the vapor pressure of a solvent above a solution is directly proportional to the mole fraction of the solvent present in the solution.

Before we proceed, let's calculate the mole fraction of chloroform in the solution.

First, calculate the moles of chloroform. Divide the mass of chloroform by its molar mass:
244.5 g chloroform / 119.40 g/mol = 2.048 moles chloroform

Next, calculate the total number of moles in the solution. This includes both chloroform and aspirin:
Total moles = moles of chloroform + moles of aspirin

You already calculated the moles of aspirin earlier:
moles of aspirin = 6.243 g aspirin / 180.1 g/mol = 0.0346 moles aspirin

So, the total moles in the solution will be:
Total moles = 2.048 moles chloroform + 0.0346 moles aspirin

Now that we have the total number of moles in the solution, we can calculate the mole fraction of chloroform:
mole fraction of chloroform = moles of chloroform / total moles

mole fraction of chloroform = 2.048 moles chloroform / (2.048 moles chloroform + 0.0346 moles aspirin)

After calculating this, you will find the mole fraction of chloroform in the solution.

Finally, use Raoult's law to calculate the vapor pressure of the solution. We know that the vapor pressure of pure chloroform is 173.11 mm Hg. Now, multiply the mole fraction of chloroform by the vapor pressure of pure chloroform to find the vapor pressure of the solution:
vapor pressure of solution = mole fraction of chloroform * vapor pressure of pure chloroform

I hope this explanation helps you to understand the calculations! Let me know if you have any further questions.