Question #e2397
1 Answer
The mass of urea is 26.1 g.
This is a freezing point depression problem.
In your problem, we have to work backwards from the freezing point to calculate the mass of solute.
Step 1. Calculate
Step 2. Calculate
Since urea is a nonelectrolyte,
Step 3. Calculate the molality
Step 4. Calculate the moles of urea
Moles of urea =
Step 5. Calculate the mass of urea
The formula of urea is NH₂CONH₂. The molar mass is 60.06 g·mol⁻¹.
Moles =
Mass = moles × molar mass = 0.435 mol × 60.06 g·mol⁻¹ = 26.1 g
The mass of urea is 26.1 g.