Question

when 0.863 mol acetone is dissolved in 500 g benzene, the freezing point of benzene drops 8.84°C. what is the molal freezing point depression constant (kf) for benzene?​

Answer 1

Answer:

• Kf = 5.12 °C/m

Explanation:

1) Data:

a) Solute: acetone

b) Solvent: benzene

c) n (solute) = 0.863 mol

d) mass of solvent = 500 g = 0.500 Kg

e) ΔTf = 8.84 °C

f) Kf = ?

2) Formulae:

• Depression of freezing point: ΔTf = m . Kf

• Molality: m = n (solute) / kg solvent

3) Solution:

a) m = 0.863 mol / 0.500 kg = 1.726 m

b) Kf = ΔTf / m = 8.84°C / 1.726 m  = 5.12 °C/m ← answer