Q: Based on the enthalpy diagrams (images 13–15), which of the following correctly represents the enthalpy change for the dissolution process?

$$\Delta H_{\text{soln}} = \Delta H_1$ + \Delta H_2$ + \Delta H_3$

Q: Refer to the energy diagram for KF dissolution (image 16). If $$|\Delta H_{\text{lattice}}| \u003e |\Delta H_{\text{hydration}}|$$, what can be said about $$\Delta H_{\text{soln}}$$?

$$\Delta H_{\text{soln}} is $$positive (endothermic)

Question 1

Which of the following best describes a solution, as shown in the first image?

Accepted Answer

A homogeneous mixture where the solute is uniformly distributed within the solvent.

Question 2

Based on the properties of glucose shown in the second image, which statement best explains why glucose is highly soluble in water?

Accepted Answer

Glucose forms strong hydrogen bonds with water due to its multiple hydroxyl groups.

Question 3

Refer to the third and fourth images. When the barrier between the two gases (Ne and Ar) is removed, what thermodynamic principle drives the mixing of the gases?

Accepted Answer

Increase in entropy ($$\Delta S)$$

Question 4

According to the fifth and sixth images, under which condition will a solution generally form?

Accepted Answer

When solvent–solute interactions are equal to or greater than the sum of solvent–solvent and solute–solute interactions.

Question 5

The seventh image shows pentane (C$$_5H$_{12}) $$and water (H$$_2O) in a $$beaker. What is the most likely observation after mixing these two liquids?

Accepted Answer

They will form two separate layers because pentane is nonpolar and water is polar.

Question 6

Which type of intermolecular force is primarily responsible for the solubility of NaCl in water, as shown in the ninth image?

Accepted Answer

Ion-dipole interactions

Question 7

Based on the enthalpy diagrams (images 13–15), which of the following correctly represents the enthalpy change for the dissolution process?

Accepted Answer

$$\Delta H_{	ext{soln}} = \Delta H_1$ + \Delta H_2$ + \Delta H_3$

Question 8

Refer to the energy diagram for KF dissolution (image 16). If $$|\Delta H_{	ext{lattice}}| \u003e |\Delta H_{	ext{hydration}}|$$, what can be said about $$\Delta H_{	ext{soln}}$$?

Accepted Answer

$$\Delta H_{	ext{soln}} is $$positive (endothermic)

Question 9

The process shown in images 17–19 (NaCl dissolving in water) eventually reaches a state where the rate of dissolution equals the rate of recrystallization. What is this state called?

Accepted Answer

Dynamic equilibrium (saturated solution)

Question 10

A student prepares a supersaturated solution of sodium acetate and adds a seed crystal, as shown in image 20. What is the most likely observation?

Accepted Answer

The solution rapidly forms sodium acetate crystals and becomes warmer.

Question 11

Which of the following best explains why the solubility of most solid solutes in water increases with temperature, but the solubility of gases decreases?

Accepted Answer

Solids dissolve endothermically, while gases dissolve exothermically.

Question 12

According to Henry's Law, what is the relationship between the concentration of a dissolved gas ($$C) $$and its partial pressure ($$P) $$above the solution?

Accepted Answer

$$C = k_H 	imes P$$

Question 13

A solution is prepared by dissolving 19.8 g of NaCl (molar mass = 58.44 g/mol) in 245 g of water. What is the molality of the solution?

Accepted Answer

$$m = 0.339\ 	ext{mol} / 0.245\ 	ext{kg} = 1.38\ m$$

Question 14

A 1.16 M solution of sucrose (C$$_{12}H$_{22}O$_{11}$$, MW = 342.3 g/mol) has a density of 1.18 g/mL. What is the molality of the solution?

Accepted Answer

$$m = 1.16\ 	ext{mol} / 0.783\ 	ext{kg} = 1.48\ m$$

Question 15

Which of the following statements about molarity and molality is correct?

Accepted Answer

Molarity is moles of solute per liter of solution; molality is moles of solute per kilogram of solvent.

Question 16

A solution contains 0.5 mol of solute and 1.5 mol of solvent. What is the mole fraction of the solute?

Accepted Answer

$$X_{	ext{solute}} = \frac{0.5}{0.5 + 1.5} = 0.25$$

Question 17

Which of the following best describes the 'like dissolves like' rule?

Accepted Answer

Substances with similar types of intermolecular forces are likely to be soluble in each other.

Question 18

Vitamin C (structure shown in image 10) is highly soluble in water, while Vitamin A (structure shown in image 11) is not. Which statement best explains this observation?

Accepted Answer

Vitamin C is hydrophilic due to its many hydroxyl groups, while Vitamin A is hydrophobic due to its long nonpolar hydrocarbon chain.

Physical Properties of Solutions: Structure, Formation, and Concentration

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