Q: Which of the following is the correct formula for calculating molality ($m$)?

$m = \dfrac{\text{moles of solute}}{\text{kilograms of solvent}}$

Question 1

Which of the following best describes a colloid?

Accepted Answer

A homogeneous mixture with large molecules or groups of molecules that do not settle out and cannot pass through semipermeable membranes.

Question 2

Which property is NOT characteristic of a suspension?

Accepted Answer

Particles are too small to be seen with the naked eye.

Question 3

A solution is prepared by dissolving 1 mole of NaCl in 1 kg of water. How many moles of solute particles are present in the solution?

Accepted Answer

$2$ moles

Question 4

Which of the following statements about colligative properties is correct?

Accepted Answer

They depend only on the concentration of solute particles.

Question 5

Calculate the molality of a solution made by dissolving $35.5$ g of glucose ($\mathrm{C_6H_{12}O_6}$, molar mass $180.16$ g/mol) in $0.400$ kg of water.

Accepted Answer

$0.493\ m$

Question 6

Which of the following mixtures would be classified as a solution?

Accepted Answer

Salt water

Question 7

A $50$–$50\%$ by mass mixture of ethylene glycol and water is used in car radiators. What is the main reason for using this mixture?

Accepted Answer

It lowers the freezing point and raises the boiling point of water.

Question 8

Which equation is used to calculate the freezing point lowering of a solution?

Accepted Answer

$\Delta T_f = m 	imes K_f$

Question 9

A solution is made by dissolving $225$ g of $\mathrm{CaCl_2}$ (molar mass $110.98$ g/mol) in $500$ g of water. How many moles of solute particles are present?

Accepted Answer

$6.08$ moles

Question 10

Which of the following best explains why you must 'shake well before using' some liquid medications?

Accepted Answer

To ensure the suspended particles are evenly distributed, forming a suspension.

Question 11

What is the new freezing point of water if $1$ mole of $\mathrm{CaCl_2}$ is dissolved in $1$ kg of water? ($K_f = 1.86\ ^\circ\mathrm{C}/m$)

Accepted Answer

$-5.58\ ^\circ\mathrm{C}$

Question 12

Which of the following statements is TRUE regarding the separation of particles in mixtures?

Accepted Answer

Suspension particles can be separated by filters.

Question 13

A solution is prepared by dissolving $4.6$ mol of propylene glycol in $1.55$ kg of water. What is the boiling point of the solution? ($K_b = 0.51\ ^\circ\mathrm{C}/m$)

Accepted Answer

$101.5\ ^\circ\mathrm{C}$

Question 14

Which of the following is an example of a real-life application of freezing point depression?

Accepted Answer

Spreading $\mathrm{CaCl_2}$ on icy roads to melt ice.

Question 15

Which mixture would NOT pass through a semipermeable membrane?

Accepted Answer

A colloid such as milk

Question 16

If $0.197$ mol of glucose is dissolved in $0.400$ kg of water, what is the molality of the solution?

Accepted Answer

$0.493\ m$

Question 17

Which of the following best describes the effect of adding a nonvolatile solute to water?

Accepted Answer

It lowers the vapor pressure, lowers the freezing point, and raises the boiling point.

Question 18

Which of the following is the correct formula for calculating molality ($m$)?

Accepted Answer

$m = \dfrac{	ext{moles of solute}}{	ext{kilograms of solvent}}$

Question 19

A water-treatment plant adds aluminum sulfate to untreated water. What is the purpose of this process?

Accepted Answer

To react with impurities and form large suspended particles (floc) that can be filtered out.

Solutions, Colloids, Suspensions, and Colligative Properties: Molality, Freezing Point Lowering, and Boiling Point Elevation

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