Quantitatively, the freezing-point depression deltaT_f of a solution is related
ID: 942564 • Letter: Q
Question
Quantitatively, the freezing-point depression deltaT_f of a solution is related to the molality m and the freezing-point-depression constant K_f of the solvent where the freezing-point depression is the difference between the freezing points of the pure solvent and the solution A solution of water (K_f=1.86degreesC/m) and glucose freezes at-3.75degreesC What is the molal concentration of glucose in this solution ? Assume that the freezing point water is 0.00degrees C Similar to he freezing-point depression, the boiling point elevation deltaT_b of a solution is quantitatively related to the molality m and the boiling-elevation constant K_b of the solvent by the equation deltaT_b=K_bm where the boiling-point elevation is the difference between the boiling points of the solution and the pure solvent. A solution of water(K_b=0.512^degreesC/m) and glucose boils at 102.06degreesC What is the molal concentration of glucose in the solution?Explanation / Answer
Glucose is a non-electrolyte, hence the vont hoff factor for glucose = 1
Depression in Freezing Point = i * KF * molality
3.75 = 1 * 1.86 * molality
molality = 2.016 m
Hence the molality of the glucose is equal to 2.016m