What is the boiling point (in °C) of a solution of 9.22 g of I2 in 66.5 g of toluene, assuming the I2 is nonvolatile? (For toluene, Tb = 110.63°C and Kb = 3.40°C·kg/mol.)
Jamie/Anne/Kenna/Sam -- please use the same name for your posts.
mols I2 - g/molar mass = ?
Solve for mols I2.
m = molality = mols I2/kg solvent. Solve for m.
delta T = Kb*m. You know Kb and m, solve for delta T.
Add delta T to the normal boiling point of toluene to find the new b.p.
Post your work if you get stuck.
Take a hint from Ms. Sue. It helps us tremendously if you use the same screen name. It get's your question(s) answered faster and with a lot less confusion. Using Anonymous as a screen name adds confusion, too.
To find the boiling point of a solution, we need to use the equation:
ΔTb = Kb × m
where ΔTb is the boiling point elevation, Kb is the molal boiling point elevation constant, and m is the molality of the solution.
First, we need to calculate the molality of the solution by dividing the moles of solute (I2) by the mass of the solvent (toluene) in kilograms.
1. Calculate the moles of I2:
- Convert the mass of I2 to moles by dividing by its molar mass.
- The molar mass of I2 is 2 * atomic mass of iodine = 2 * (126.90 g/mol) = 253.80 g/mol.
- Moles of I2 = mass of I2 / molar mass of I2.
2. Calculate the mass of toluene in kilograms:
- Toluene's mass is given as 66.5 grams.
- Convert this to kilograms by dividing by 1000.
3. Calculate the molality:
- Molality (m) = moles of I2 / mass of toluene (in kg).
4. Calculate the boiling point elevation (ΔTb):
- ΔTb = Kb × m
5. Finally, calculate the boiling point of the solution:
- Boiling point of the solution = boiling point of the pure solvent (toluene) + ΔTb.
Let's perform the calculations to find the boiling point of the solution:
1. Moles of I2 = 9.22 g / 253.80 g/mol = 0.0363 mol.
2. Mass of toluene in kilograms = 66.5 g / 1000 = 0.0665 kg.
3. Molality (m) = 0.0363 mol / 0.0665 kg = 0.546 mol/kg.
4. ΔTb = 3.40°C·kg/mol × 0.546 mol/kg = 1.8554°C.
5. Boiling point of the solution = boiling point of toluene (110.63°C) + ΔTb = 110.63°C + 1.8554°C = 112.48°C.
Therefore, the boiling point of the solution is 112.48°C.