Worksheet: Cryoscopic and Ebullioscopic Effects

In this worksheet, we will practice using cryoscopic and ebullioscopic constants to calculate how solutes affect solution melting and boiling points.

Q1:

What is the boiling point of a solution of 115.0 g of sucrose, CHO122211, in 350.0 g of water? The boiling point elevation constant of water is 0.512/∘Cm.

Q2:

What is the boiling point elevation of 0.100 kg of water containing 0.0100 mol of NaCl, 0.0200 mol of NaSO24, and 0.0300 mol of MgCl2? Assume complete dissociation of the salts.

Q3:

A sample of HgCl2 weighing 9.41 g is dissolved in 32.75 g of ethanol, CHOH25 (𝐾=1.20⋅/)bKkgmol. The boiling point elevation of the solution is 1.27∘C. Is HgCl2 an electrolyte in ethanol?

  • ANo, the boiling point elevation is consistent with HgCl2 completely dissociating.
  • BYes, the boiling point elevation is consistent with HgCl2 completely dissociating.
  • CYes, the boiling point elevation is consistent with HgCl2 partially dissociating.
  • DNo, the boiling point elevation is consistent with HgCl2 not dissociating at all.
  • EYes, the boiling point elevation is consistent with HgCl2 not dissociating at all.

Q4:

What is the boiling point of a solution of NaCl in water if the solution freezes at −0.93∘C? The cryoscopic constant of water is 1.853 K⋅kg/mol and the ebullioscopic constant is 0.512 K⋅kg/mol.

Q5:

What is the boiling point of a solution of 115.0 g of sucrose, CHO122211, in 350.0 g of water? The boiling point elevation constant of water is 0.512 K⋅kg/mol.

Q6:

Which of the following will have the lowest freezing point?

  • AA 0.01 M aqueous solution of NaCl
  • BA 0.01 M aqueous solution of BaCl2
  • CA 0.01 M aqueous solution of FeCl3
  • DA 0.01 M aqueous solution of CuCl2
  • EA 0.01 M aqueous solution of KBr

Q7:

If a 1.00 M solution of NaCl in water shows a freezing-point depression of 3.72∘C, what is the freezing-point depression observed for a 1.00 M solution of CaCl2 in water? The ions of both NaCl and CaCl2 completely dissociate in aqueous solution.

Q8:

Which of the following will have the highest boiling point?

  • AA 0.1 M aqueous solution of KCl
  • BA 0.01 M aqueous solution of BaCl2
  • CA 0.1 M aqueous solution of CaCl2
  • DA 0.1 M aqueous solution of sucrose

Q9:

Which of the following has the lowest boiling point?

  • AA 12 M aqueous solution of sulfuric acid
  • BA 0.01 M aqueous solution of NaHCO3
  • CPure liquid water
  • DA 0.1 M aqueous solution of glucose

Q10:

What is the freezing temperature of a solution of 115.0 g of sucrose, CHO122211, in 350.0 g of water? The freezing point depression constant for water is 1.86 kg⋅K/mol.

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