Solute A associates in water. When 0.7 g of solute is dissolved in 42 g of water, it depresses the freezing point by 0.2^oC. What is the percentage association of solute A in water? (Given: Molar mass of A = 93 g/mol, K_f = 1.86 K kg/mol)

80%

Since, ΔT_f = i Kf m

m = \(\frac{0.7}{93}\) x \(\frac{1000}{42}\)

0.2 = i x 1.86 x \(\frac{0.7}{93}\) x \(\frac{1000}{42}\)

i = 0.6

α = \(\frac{i - 1}{\frac{1}{n} - 1}\)

α = \(\frac{0.6 - 1}{\frac{1}{2} - 1}\) = 0.8

Hence, percentage association of solute is 80%.