Q: Which of the following is the correct formula for calculating molarity (M)?

$$M = \frac{\text{moles solute}}{\text{vol(L) solution}}$$

Q: Which of the following is the correct formula for calculating mole fraction ($$X_A) of a $$component A?

$$X_A = \frac{\text{mol}_A}{\text{mol}_{\text{total}}}$$

Question 1

Which of the following statements best describes a colligative property?

Accepted Answer

A property that depends on the quantity but not the kind of solute particles.

Question 2

A solution is prepared by dissolving 13.5 g of glucose (C$$_6H$_{12}O$_6) in 0.100 kg of $$water. What is the mass percent of glucose in the solution? Use the formula $$	ext{Mass percent} = \frac{	ext{mass of solute}}{	ext{mass of solution}} 	imes 100\%.$$

Accepted Answer

$$11.9\%$$

Question 3

Which intermolecular force is primarily responsible for the high boiling point of water compared to other Group 16 hydrides?

Accepted Answer

Hydrogen bonding

Question 4

At the top of Mt. Everest, the atmospheric pressure is 240 torr and the boiling point of water is 70$$^\circC. $$Why does water boil at a lower temperature at high altitudes?

Accepted Answer

The external pressure is lower, so water boils when its vapor pressure equals the lower atmospheric pressure.

Question 5

Which of the following best explains why solid CO$$_2 ($$dry ice) sublimes rather than melts at atmospheric pressure?

Accepted Answer

The triple point of CO$$_2 is $$above atmospheric pressure, so it cannot exist as a liquid at 1 atm.

Question 6

Which of the following equations correctly expresses the freezing point depression for an electrolyte solution?

Accepted Answer

$$\Delta T_f = -iK_f m$$

Question 7

A 1 m aqueous solution of NaCl has a higher boiling point elevation than a 1 m solution of sucrose. Why?

Accepted Answer

NaCl dissociates into two ions, increasing the van’t Hoff factor $$i.$$

Question 8

Which of the following is the correct formula for calculating molarity (M)?

Accepted Answer

$$M = \frac{	ext{moles solute}}{	ext{vol(L) solution}}$$

Question 9

Which of the following best describes osmosis?

Accepted Answer

The movement of solvent molecules from a region of lower solute concentration to higher solute concentration through a semipermeable membrane.

Question 10

Which of the following is the correct expression for osmotic pressure ($$\Pi) of a $$solution?

Accepted Answer

$$\Pi = MRT$$

Question 11

Which of the following molecules can form hydrogen bonds with water?

Accepted Answer

NH$$_3$$

Question 12

A solution contains 36% HCl by mass. What is the mole fraction of HCl in the solution? (Molar mass: HCl = 36.5 g/mol, H$$_2O = 18.0 g/$$mol)

Accepted Answer

0.22

Question 13

Which of the following statements about dispersion forces is correct?

Accepted Answer

They arise from instantaneous dipoles in atoms or molecules.

Question 14

Which of the following best explains why a pressure cooker is useful for cooking at high altitudes?

Accepted Answer

It increases the external pressure, raising the boiling point of water.

Question 15

Which of the following is NOT a colligative property?

Accepted Answer

Color of the solution

Question 16

A solution is made by dissolving 0.99 mol HCl in 0.064 kg H$$_2O. $$What is the molality of HCl in the solution?

Accepted Answer

$$15\, m$$

Question 17

Which of the following best describes the triple point on a phase diagram?

Accepted Answer

The temperature and pressure where all three phases (solid, liquid, gas) coexist in equilibrium.

Question 18

Which of the following is the correct formula for calculating mole fraction ($$X_A) of a $$component A?

Accepted Answer

$$X_A = \frac{	ext{mol}_A}{	ext{mol}_{	ext{total}}}$$

Properties of Solutions: Phase Transitions, Concentration, and Colligative Properties

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