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
Is this correct so far? I do not know how to convert solvent to mole fraction.
See your other post above.
Yes, you are correct so far!
To calculate the vapor pressure of the solution, you need to calculate the mole fraction of the solute (aspirin) and the solvent (chloroform).
Mole fraction (X) of a component is defined as the moles of that component divided by the total moles of all components in the solution.
First, calculate the moles of aspirin using the given mass and molar mass:
Moles of aspirin = mass of aspirin / molar mass of aspirin
= 6.243g / 180.1g/mol
= 0.0346 moles
Next, calculate the moles of chloroform using the given mass and molar mass:
Moles of chloroform = mass of chloroform / molar mass of chloroform
= 244.5g / 119.4g/mol
= 2.0498 moles
Now, you can calculate the mole fraction of the solvent (chloroform) using the equation:
Mole fraction of chloroform (Xch) = Moles of chloroform / (Moles of aspirin + Moles of chloroform)
= 2.0498 moles / (0.0346 moles + 2.0498 moles)
= 0.9837
The mole fraction of the solute (aspirin) can be calculated by subtracting the mole fraction of the solvent from 1:
Mole fraction of aspirin (Xas) = 1 - Mole fraction of chloroform
= 1 - 0.9837
= 0.0163
Now, you can use these mole fractions to calculate the vapor pressure of the solution using Raoult's law.
Raoult's law states that the vapor pressure of a solution is equal to the mole fraction of the solvent multiplied by the vapor pressure of the pure solvent.
Vapor pressure of solution = Mole fraction of chloroform * Vapor pressure of chloroform
Vapor pressure of chloroform is given as 173.11 mm Hg.
Vapor pressure of solution = 0.9837 * 173.11 mm Hg
= 170.06 mm Hg
Therefore, the vapor pressure of the solution at 25 degrees Celsius when 6.243g of aspirin are dissolved in 244.5g of chloroform is approximately 170.06 mm Hg.