What is the boiling point of a solution of 0.515 grams of acenaphthene (C12H10) in 15 grams chloroform (CHCl3) given pure chloroform has a b.p. of 61.7 C and a Kbp of +3.63 C.
Thanks!
mols C12H10 = grams/molar mass.
Solve for mols.
m = molality = mols/kg solvent.
Solve for m
delta T = Kb*m
Solve for delta T.
Add delta T to the normal boiling point to find the new boiling point.
Molar mass of C12H10 is 154.2078 g/mols
C12H10 = .003 mols
.2 molal
delta T = 123. 4 C
nope. I didn't work it through but that's way too large an amount.
If I divide 0.515/154 = about 0.00334 and that divided by 0.015 = about 0.223.
I don't know why you threw two perfectly numbers away (the 23 of the 0.223) but that's in the ball park. So your mistake must be in the next to last step.
delta T = Kb*m
Is this right?
Delta T= (3.63C)(.223)= .809 C
Yes. Now to find the new boiling point just add delta T to the normal boiling point given in the problem.
Thank you so much for your help! :)
To find the boiling point of the solution, you can use the equation:
ΔTb = i * Kbp * m
Where:
ΔTb is the change in boiling point
i is the van't Hoff factor (the number of particles the solute dissociates into when it dissolves in the solvent)
Kbp is the boiling point elevation constant (in this case, it is +3.63 °C/mol)
m is the molality of the solution (moles of solute/kg of solvent)
First, calculate the molality of the solution using the given masses:
molality (m) = moles of solute / kg of solvent
The molar mass of acenaphthene (C12H10) can be calculated as follows:
(12.01 g/mol * 12) + (1.01 g/mol * 10) = 152.18 g/mol
Thus, the moles of acenaphthene can be calculated as:
moles of acenaphthene = mass / molar mass
= 0.515 g / 152.18 g/mol
The moles of chloroform can be calculated as:
moles of chloroform = mass / molar mass
= 15 g / 119.38 g/mol
Next, calculate the molality of the solution:
moles of solute = moles of acenaphthene
moles of solvent = moles of chloroform
molality = moles of solute / kg of solvent
Now that you have the molality of the solution, you can calculate the change in boiling point (ΔTb) using the equation mentioned earlier.
Finally, to find the boiling point of the solution, add the change in boiling point to the boiling point of pure chloroform (61.7 °C).
The boiling point of the solution can be calculated using the formula:
Boiling point of the solution = Boiling point of pure solvent + ΔTb.
I hope this explanation helps you find the boiling point of your solution!