Answer to Question #139288 in General Chemistry for jane

Question

Calculate the molar mass of the solute in a solution of 2.47 g of a mo electrolyte in 100 g of acetic acid (CH3COO). The solution freezes at 1.3 °C below the normal freezing point of pure acetic acid. (Kf for CH3COOH=3.9°C/m)

Answer 1

∆T=K_fC_m

C_m=∆T/K_f=1.3/3.9=0.3(mol/kg)

C_m=n_solute/m_solvent

n_solute=C_mm_solvent=0.3•0.1=0.03(mol)

M=m/n=2.47/0.03=82.33(g/mol)