Advertisements
Advertisements
Question
An aqueous solution of urea freezes at – 0.186°C, Kf for water = 1.86 K kg mo1–1, Kb for water = 0.512 K kg mo1–1. The boiling point of urea solution will be:
Options
373.065 K
373.186 K
373.512 K
373.0512 K
Solution
373.0512
[0- (-0.186)] = 1.86 x m
`:. m = (0.186)/1.86 = 0.1`
`triangleT_b = K_b.m`
`:. triangleT_b = 0.512 xx 0.1`
= 0.0512
`T - T^@ = 0.0512`
`T = 0.0512 + T^@`
= 0.0512 + 373
= 373.01512 K
APPEARS IN
RELATED QUESTIONS
Ethylene glycol is used as an antifreeze agent. Calculate the amount of ethylene glycol to be added to 4 kg of water to prevent it from freezing at -6°C. (Kf for H2O = 1 .85 K mole-1 kg)
A 5% aqueous solution (by mass) of cane sugar (molar mass 342 g mol-1) has a freezing point of 271 K. Calculate the freezing point of 5% aqueous glucose solution.
Freezing point depression constant of a solvent is _______.
What is a cryoscopic constant?
Write the effect of dissolution of a nonvolatile solute on the freezing point of solvent.
Calculate total moles after dissociation in 0.1 M KCl solution and 0.05 M aluminium sulphate solution. Hence, decide which of the two solutions will have higher freezing point depression.
Explain with vapour pressure-temperature curves that the freezing point of a solvent is lowered by dissolving a nonvolatile solute into it. Give reason for such lowering of freezing of solvent.
Write the SI unit of the cryoscopic constant.
Calculate the mass of compound to be dissolved in 75g of benzene to lower its freezing point by 0.48 K. (Given: Kf = 0.512 K kg mol-1 and molar mass = 256g mol-1)
Calculate the mass of ascorbic acid (molecular mass = 176 g/mol) that should be dissolved in 155 g of acetic acid to cause a depression of the freezing point by 1.15 K. Assume that ascorbic acid does not dissociate or associate in the solution. (Kf for acetic acid = 3.9 K kg/mol)
