What is the molecular mass of a non-ionizing solid if 10 g of this solid, when dissolved in 100 g of water, forms a solution, which freezes at -1.24°C? () = 1.86°C kg mol^-1.

Question

What is the molecular mass of a non-ionizing solid if 10 g of this solid, when dissolved in 100 g of water, forms a solution, which freezes at -1.24°C? $K_f$($H_2O$) = 1.86°C kg mol^-1.

Prashant Kotian · Accepted Answer

Correct answer: B. Depression in freezing point ΔT_f = 1.24°C. Using the formula: ΔT_f = * m = * (w_solute / M_solute) * (1000 / W_solvent) => 1.24 = 1.86 * (10 / M) * (1000 / 100) => 1.24 = 1.86 * (100 / M) = 186 / M => M = 186 / 1.24 = 150 g/mol.

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