Question 1

Which of the following best describes the phenomenon of boiling point elevation?

Accepted Answer

The boiling point of a pure solvent increases when a solute is added.

Question 2

Which equation correctly represents the boiling point elevation for a solution?

Accepted Answer

$$\Delta T_b = K_b \cdot m \cdot i$$

Question 3

A solution is prepared by dissolving a non-volatile solute in water. Which of the following will increase as a result?

Accepted Answer

The boiling point of the solution

Question 4

If 13.12 g of aluminum chloride ($$\mathrm{$$AlCl_3$$}) is $$added to 615 g of water, which value is needed to determine the boiling point elevation?

Accepted Answer

The van't Hoff factor ($$i) $$for $$\mathrm{$$AlCl_3$$}$$

Question 5

What is the van't Hoff factor ($$i) $$for a compound that is covalent and non-electrolytic in water?

Accepted Answer

$$i = 1$$

Question 6

A solution is made by dissolving 25.2 g of ethylene glycol ($$\mathrm{C_2H_6O_2}) in 101.5 mL of $$water. What is the first step in calculating the change in boiling point?

Accepted Answer

Convert the mass of ethylene glycol to moles.

Question 7

Which of the following best explains why the boiling point of a solution is higher than that of the pure solvent?

Accepted Answer

The solute decreases the vapor pressure, requiring a higher temperature to boil.

Question 8

If the boiling point elevation constant ($$K_b) $$for water is $$0.512\ \mathrm{^\circ C\,kg\,$$mol^{-1}$$}$$, what is the boiling point of a solution containing 1.00 mol of a non-electrolyte in 1.00 kg of water?

Accepted Answer

$$100.512\ ^\circ \mathrm{C}$$

Question 9

A glucose solution in water has a boiling point of $$103.15\ ^\circ \mathrm{C}. If $$the $$K_b$$ for water is $$0.512\ \mathrm{^\circ C\,kg\,$$mol^{-1}$$}$$, what is the molality of the solution? (Assume $$i = 1$$ for glucose.)

Accepted Answer

$$6.16\ \mathrm{m}$$

Question 10

Which of the following would result in the greatest boiling point elevation when dissolved in 1 kg of water?

Accepted Answer

1 mol of aluminum chloride ($$i = 4)$$

Question 11

A solution is prepared by dissolving carbon dioxide in 722 mL of toluene. If the density of toluene is $$0.866\ \mathrm{g/mL}$$, what is the mass of toluene used?

Accepted Answer

$$626\ \mathrm{g}$$

Question 12

Which of the following statements about colligative properties is correct?

Accepted Answer

They depend on the number of solute particles present.

Question 13

If a solution is made by dissolving 10 g of NaCl in 500 g of water, which of the following is needed to calculate the boiling point elevation?

Accepted Answer

All of the above

Question 14

A student claims that adding more solute to a solution will always increase its boiling point. Which scenario would make this statement incorrect?

Accepted Answer

Adding a volatile solute

Question 15

Which of the following is the correct sequence of steps to solve for the boiling point of a solution?

Accepted Answer

Find moles of solute, calculate molality, use $$\Delta T_b = K_b m i$$, add to pure solvent boiling point

Question 16

A solution is made by dissolving a solute in water. The solution boils at $$101.5\ ^\circ \mathrm{C}. If $$the boiling point elevation constant for water is $$0.512\ \mathrm{^\circ C\,kg\,$$mol^{-1}$$}$$, what is the boiling point elevation?

Accepted Answer

$$1.5\ ^\circ \mathrm{C}$$

Boiling Point Elevation: Concepts and Calculations

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