1,2-Benzanthracene is a yellow-brown nonvolatile solid with molecular weight 228.29g*mol-1. an 18.2632-g sample of 1,2-benzanthracene is dissolved in 250.0 g of benzene, C6H6. Whta is the vapor pressure of this solution at 25C, in millimeters of mergury, if the vapor pressure of pure benzene is 93.4 mmHg at this temperature?
a)60.8
b)91.1
c)93.4
d)95.7
e)760
This was on my last test but i got it wrong. This is for test corrections and the right answer is (b) but i have absolutely no idea how to do this. Thank you so much for whoever attempts to help. :)
Yes, the answer is b.
mols BZth = grams/molar mass = ?
mols benzene = grams/molar mass = ?
Xbenzene = mols benzene/total mols.
Then pbenzene soln = Xbenzene*Pbenzene where Pbenzene is 93.4 mm = normal vapor pressure.
To find the vapor pressure of the solution, you can use Raoult's Law. Raoult's Law states that the partial pressure of a component in a solution is equal to the vapor pressure of the pure component multiplied by its mole fraction in the solution.
First, we need to calculate the mole fraction of benzene in the solution. The mole fraction (X) is calculated by dividing the moles of benzene by the total moles of all components in the solution.
To find the moles of benzene, we can use the formula:
moles = mass / molar mass
Given:
Mass of benzene solution = 250.0 g
Molar mass of benzene (C6H6) = 78.11 g/mol
moles of benzene = 250.0 g / 78.11 g/mol
Now, let's calculate the moles of 1,2-benzanthracene. We can use the same formula:
moles of 1,2-benzanthracene = mass / molar mass
Given:
Mass of 1,2-benzanthracene = 18.2632 g
Molar mass of 1,2-benzanthracene = 228.29 g/mol
moles of 1,2-benzanthracene = 18.2632 g / 228.29 g/mol
Next, we need to calculate the total moles of all components in the solution by summing up the moles of benzene and 1,2-benzanthracene.
total moles = moles of benzene + moles of 1,2-benzanthracene
Now, we can calculate the mole fraction of benzene:
mole fraction of benzene = moles of benzene / total moles
Once we have the mole fraction, we can calculate the vapor pressure of the solution using Raoult's Law:
vapor pressure of solution = mole fraction of benzene * vapor pressure of pure benzene
Given:
vapor pressure of pure benzene = 93.4 mmHg
Finally, convert the vapor pressure from mmHg to mm of mercury.
Now, compare the calculated vapor pressure of the solution with the options provided (a, b, c, d, e) and select the correct answer. In this case, the correct answer is (b) 91.1 mmHg.