What is the boiling point of a solution containing
0.80 g caffeine,C₈H₁₀N₄O₂,dissolved in 13.20 g benzene? The boiling point of pure benzene is 80.1°C and the molal boiling point constant,K_b,is 2.53°C/m.

Question

Quizplus · Accepted Answer

First, we need to calculate the molality of the solution:
molality (m) = (0.80 g / 194.19 g/mol) / (13.20 g / 78.11 g/mol) = 0.0574 mol/kg

Next, we can use the formula for boiling point elevation:

ΔTb = Kb x m

where ΔTb is the boiling point elevation, Kb is the molal boiling point constant, and m is the molality of the solution.

ΔTb = 2.53°C/m x 0.0574 mol/kg = 0.145°C

Finally, we can calculate the boiling point of the solution:

boiling point = 80.1°C + 0.145°C = 80.245°C

Round to one decimal place: 80.2°C

The closest option is C) 80.9°C.

What Is the Boiling Point of a Solution Containing