Q: Which of the following is the correct expression for molality ($$m) of a $$solution?

$$m = \frac{\text{moles of solute}}{\text{kg of solvent}}$$

Question 1

Which of the following best describes the difference between oxidation state and formal charge for an atom in a molecule?

Accepted Answer

Oxidation state assigns all bonding electrons to the more electronegative atom, while formal charge assumes equal sharing of electrons in bonds.

Question 2

Which of the following statements about the phase diagram of water is correct?

Accepted Answer

The triple point is where solid, liquid, and gas phases coexist at equilibrium.

Question 3

A solution is prepared by dissolving 1.2 kg of ethylene glycol (molar mass = 62.1 g/mol) in 4.0 kg of water, resulting in a total solution volume of 4.1 L. What is the molality ($$m) of $$ethylene glycol in the solution?

Accepted Answer

$$m = \frac{19.3}{4.0} = 4.82$$

Question 4

Which of the following best explains why the boiling point of a solvent increases when a nonvolatile solute is added?

Accepted Answer

The solute decreases the vapor pressure of the solvent, requiring a higher temperature to reach atmospheric pressure.

Question 5

Which of the following is a correct application of Raoult’s Law for a solution?

Accepted Answer

$$P_{solvent,solution} = \chi_{solvent} \cdot P_{solvent}^{*}$$

Question 6

Which of the following salts is expected to be soluble in water according to the solubility rules provided?

Accepted Answer

Na$$_2SO$_4$$

Question 7

A 0.02 m aqueous solution of a salt freezes at $$-0.0640\ ^\circC. If$$ $$k_{fp} = -1.86\ ^\circC/m $$for water, what is the van’t Hoff factor $$i$$ for this salt?

Accepted Answer

$$i = 1.72$$

Question 8

Which of the following best describes the difference between crystalline and amorphous solids?

Accepted Answer

Crystalline solids have a regular repeating 3D lattice structure, while amorphous solids lack long-range order.

Question 9

Which of the following equations correctly relates the vapor pressures at two temperatures using the Clausius-Clapeyron equation?

Accepted Answer

$$\ln \left( \frac{P_1$}{P_2$} \right) = \frac{\Delta H_{vap}}{R} \left( \frac{1}{T_2$} - \frac{1}{T_1$} \right)$$

Question 10

Which of the following best explains why the van’t Hoff factor $$i$$ for NaCl in water is less than 2 at higher concentrations?

Accepted Answer

Because the activity of ions decreases due to increased ion pairing and interactions at higher concentrations.

Question 11

Which of the following is the correct expression for molality ($$m) of a $$solution?

Accepted Answer

$$m = \frac{	ext{moles of solute}}{	ext{kg of solvent}}$$

Question 12

A sample of water is cooled from 125°C to -25°C at 1 atm. Which step releases the greatest amount of heat to the surroundings?

Accepted Answer

Condensing 2 mol of steam at 100°C to liquid water.

Question 13

Which of the following best describes the effect of increasing temperature on the solubility of a gas in water, assuming dissolution is exothermic?

Accepted Answer

The solubility decreases because the system shifts to release the added heat, favoring the gas phase.

Question 14

Which of the following is a colligative property?

Accepted Answer

Boiling point elevation

Question 15

Which of the following best describes the molecular-level process when NaCl dissolves in water?

Accepted Answer

Na$$^+$$ and Cl$$^-$$ ions are separated and surrounded by water molecules, forming hydration shells.

Question 16

Which of the following is true about the kinetic energy distribution of molecules in a liquid as temperature increases?

Accepted Answer

The distribution shifts to higher energies and becomes broader.

Question 17

Which of the following best explains why ice floats on water?

Accepted Answer

Ice is less dense than liquid water because its hydrogen-bonded structure creates more open space.

General Chemistry: Module 1 Study Guide

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