AP Chemistry Quiz: Solutions And Mixtures

What this quiz covers

This quiz focuses on Solutions And Mixtures, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Chemistry.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. A homogeneous solution forms; water is the solute and $\text{CaCO}_3$ is the solvent.
2. A homogeneous solution forms; $\text{CaCO}_3$ is the solvent because it is a solid.
3. No homogeneous solution forms because stirring cannot produce solutions.
4. No homogeneous solution forms because $\text{CaCO}_3$ is only sparingly soluble in water. (correct answer)
5. A homogeneous solution forms; the solvent is the substance with the higher molar mass.

Explanation: This question tests knowledge of solubility limits for ionic compounds and recognition of sparingly soluble substances. Adding 1.0 g of CaCO3 to 100 mL of water results in undissolved solid remaining because CaCO3 has very low solubility in water (about 0.0013 g/100 mL at room temperature), preventing a homogeneous solution from forming despite stirring. This is due to the strong lattice energy in CaCO3 not being sufficiently overcome by hydration energy in water. The mixture remains heterogeneous with precipitate at the bottom. A tempting distractor is choice A, suggesting a homogeneous solution with reversed roles, but this stems from the misconception that all ionic solids are highly soluble in water without checking specific solubility data. A transferable strategy is to consult solubility rules or tables for ionic compounds to predict if a given amount will fully dissolve.

Question 2

1. A homogeneous solution forms; water is the solvent and $\text{KNO}_3$ is the solute. (correct answer)
2. A homogeneous solution forms; $\text{KNO}_3$ is the solvent and water is the solute.
3. A homogeneous solution forms; the solvent is the component present in fewer moles.
4. No homogeneous solution forms because ionic compounds cannot dissolve at elevated temperature.
5. No homogeneous solution forms because heating prevents dissolution by increasing particle motion.

Explanation: This question tests the effect of temperature on solubility of ionic compounds and identification of solution components. Adding 3.0 g of KNO3 to 100 mL of water at 60°C forms a homogeneous solution because KNO3 has high solubility in water, which increases with temperature (about 100 g/100 mL at 60°C), allowing full dissolution with stirring. Water is the solvent as the abundant liquid, and KNO3 is the solute, following standard definitions where the dissolved solid is the solute. The elevated temperature provides more kinetic energy to break ionic bonds and enhance solvation. A tempting distractor is choice B, claiming no solution due to temperature effects, but this reflects the misconception that heat always reduces solubility, whereas for most solids like KNO3, it increases it. A transferable strategy is to reference solubility curves for temperature-dependent dissolution predictions.

Question 3

1. Sucrose is the solvent because it is the solid and water is the solute.
2. Water is the solvent and sucrose is the solute in a homogeneous solution. (correct answer)
3. Water is the solute because it is the larger volume, and sucrose is the solvent.
4. No solution forms because covalent compounds cannot dissolve in water.
5. Two layers form because sucrose is nonpolar and water is polar.

Explanation: This question tests identification of solute and solvent in a sugar solution. When sucrose dissolves in water, it forms a homogeneous solution with water as the solvent (the liquid medium present in greater amount) and sucrose as the solute (the solid being dissolved). Sucrose, despite being a covalent compound, dissolves well in water because it has multiple -OH groups that can hydrogen bond with water molecules. Choice D incorrectly claims covalent compounds cannot dissolve in water, when many polar covalent compounds (like sugars and alcohols) are highly water-soluble. Remember that solubility depends on intermolecular forces, not just whether a compound is ionic or covalent.

Question 4

1. Two layers form because ethanol is nonpolar and water is polar.
2. A homogeneous solution forms because ethanol and water can hydrogen-bond. (correct answer)
3. A heterogeneous mixture forms because molecular compounds cannot dissolve in water.
4. Two layers form because ethanol is denser than water.
5. A homogeneous solution forms, with ethanol as the solvent because it is added first.

Explanation: This question tests understanding of miscibility between polar molecules. Ethanol (C2H5OH) and water are both polar molecules capable of hydrogen bonding - ethanol has an -OH group that can both donate and accept hydrogen bonds with water molecules. This strong intermolecular interaction allows them to mix in all proportions, forming a homogeneous solution. Choice A incorrectly claims ethanol is nonpolar, when the presence of the hydroxyl (-OH) group makes it polar. When predicting miscibility, look for similar intermolecular forces - molecules that can engage in the same types of interactions (especially hydrogen bonding) tend to be miscible.

Question 5

1. A homogeneous solution forms, with CaCO$_3$ as the solvent and water as the solute.
2. A homogeneous solution forms, with water as the solvent and CaCO$_3$ as the solute.
3. A heterogeneous mixture forms because CaCO$_3$ is insoluble enough that undissolved solid remains. (correct answer)
4. A heterogeneous mixture forms, but it is still called a solution because it was stirred.
5. A homogeneous solution forms because all ionic compounds fully dissolve in water.

Explanation: This question tests understanding of solubility limits and heterogeneous mixture formation. CaCO₃ (calcium carbonate) has extremely low solubility in water at room temperature (approximately 0.001 g per 100 mL), so 1.0 g in 50 mL far exceeds its solubility limit. When a solid's solubility limit is exceeded, undissolved solid remains, creating a heterogeneous mixture with both dissolved ions in solution and solid particles that settle. The presence of visible solid after stirring confirms that the mixture is heterogeneous, not homogeneous. Choice E incorrectly assumes all ionic compounds fully dissolve in water, but many ionic compounds like CaCO₃, BaSO₄, and AgCl have very low water solubility despite being ionic. When mixing solids with liquids, check solubility data - if the amount added exceeds the solubility limit, expect a heterogeneous mixture with undissolved solid.

Question 6

1. A homogeneous solution forms, and water is the solvent. (correct answer)
2. A heterogeneous mixture forms because CO2 is nonpolar.
3. A heterogeneous mixture forms because gases cannot dissolve in liquids.
4. A homogeneous solution forms, and water is the solute.
5. A homogeneous solution forms, and CO2 is the solvent.

Explanation: This question tests the skill of recognizing gas solubility in liquids and identifying the solvent in gaseous solute systems. Carbon dioxide gas dissolves in water to form a clear, homogeneous solution, as CO2 molecules interact with water via dipole-induced dipole forces, and no bubbles are visible after shaking. In this solution, water is the solvent as it is the liquid medium containing the dissolved gas. The capped container and shaking enhance dissolution by increasing pressure and contact. A tempting distractor is choice B, which identifies CO2 as the solvent, arising from the misconception that the gaseous component acts as the solvent. To determine solution types with gases, consider the liquid as the solvent and check for uniformity and absence of phases to confirm homogeneity.

Question 7

1. A heterogeneous mixture forms because solids cannot dissolve in liquids.
2. A homogeneous solution forms, and iodine is the solvent.
3. A heterogeneous mixture forms because nonpolar solutes only dissolve in polar solvents.
4. A homogeneous solution forms, and iodine is the solvent because it provides the color.
5. A homogeneous solution forms, and hexane is the solvent. (correct answer)

Explanation: This question tests the skill of applying the 'like dissolves like' rule to predict solubility and identify solvents in nonpolar systems. Iodine, a nonpolar molecular solid, dissolves in hexane, a nonpolar solvent, forming a uniformly purple mixture because their similar nonpolar natures allow for dispersion forces to facilitate dissolution. In this homogeneous solution, hexane is the solvent as it is the liquid medium in larger amount. The uniform color without visible solids confirms complete dissolution. A tempting distractor is choice B, which identifies iodine as the solvent, based on the misconception that the colored or solid component dictates the solvent role. When dealing with nonpolar solutes and solvents, use the 'like dissolves like' principle and identify the solvent as the predominant liquid component to classify the mixture accurately.

Question 8

1. A homogeneous solution forms; water is the solvent and NaCl is the solute. (correct answer)
2. A homogeneous solution forms; NaCl is the solvent and water is the solute.
3. No homogeneous solution forms because ionic compounds cannot dissolve in polar solvents.
4. No homogeneous solution forms because water and NaCl are both polar substances.
5. A homogeneous solution forms; both NaCl and water are solvents because both are present.

Explanation: This question tests the understanding of solubility principles, specifically how ionic compounds interact with polar solvents and the identification of solvent versus solute. When 2.0 g of NaCl, an ionic compound, is added to 50 mL of water, a polar solvent, it dissolves completely due to the 'like dissolves like' rule, where the polar water molecules can effectively solvate the Na+ and Cl- ions, forming a homogeneous solution. Water is identified as the solvent because it is present in a much larger quantity compared to NaCl, which is the solute as the dissolved substance. The stirring helps in dispersing the ions evenly throughout the solution. A tempting distractor is choice B, which incorrectly identifies NaCl as the solvent and water as the solute, stemming from the misconception that the solid must be the solvent due to its state of matter rather than considering the relative amounts. A transferable strategy is to always evaluate the polarity of substances and the relative quantities to determine solubility and roles in a solution.

Question 9

1. A homogeneous solution forms; ethanol is the solvent and water is the solute.
2. A homogeneous solution forms; water is the solvent and ethanol is the solute. (correct answer)
3. No homogeneous solution forms because ethanol is polar and water is polar.
4. No homogeneous solution forms because two liquids cannot form a solution.
5. A homogeneous solution forms; both ethanol and water are solutes in each other.

Explanation: This question tests the identification of solvent and solute in miscible liquid mixtures and the principles of solubility for polar substances. Adding 1.0 mL of ethanol, a polar molecule capable of hydrogen bonding, to 99 mL of polar water results in a homogeneous solution because both substances have similar intermolecular forces, allowing them to mix uniformly according to 'like dissolves like'. Water is the solvent as it constitutes the vast majority of the mixture by volume, while ethanol is the solute being dissolved in it. The stirring ensures even distribution, leading to a uniform appearance. A tempting distractor is choice A, which reverses the solvent and solute, based on the misconception that the added substance is always the solvent regardless of quantity. A transferable strategy is to designate the component in the greatest amount as the solvent in mixtures of similar polarity.

Question 10

1. No homogeneous solution forms because covalent compounds cannot dissolve in water.
2. A homogeneous solution forms; sucrose is the solvent and water is the solute.
3. A homogeneous solution forms; water is the solvent and sucrose is the solute. (correct answer)
4. No homogeneous solution forms because sugar molecules are too large to dissolve.
5. A homogeneous solution forms; both substances are solvents because both are present in large amounts.

Explanation: This question tests the solubility of polar covalent compounds in polar solvents and correct identification of solution components. Mixing 5.0 g of sucrose, a polar molecular solid with multiple OH groups, into 20 mL of polar water forms a homogeneous solution because the similar polar natures allow hydrogen bonding interactions, adhering to 'like dissolves like', resulting in a clear mixture after stirring. Water serves as the solvent due to its larger quantity, while sucrose is the solute being dissolved. The process is facilitated by the breakdown of sucrose crystals into molecules dispersed in water. A tempting distractor is choice B, which incorrectly labels sucrose as solvent, arising from the misconception that the solid component is always the solvent based on physical state rather than amount. A transferable strategy is to consider molecular polarity and hydrogen bonding capability when predicting dissolution of organic compounds in water.

Question 11

1. A homogeneous solution forms, and sucrose is the solvent.
2. A homogeneous solution forms, and water is the solvent. (correct answer)
3. A heterogeneous mixture forms because covalent compounds do not dissolve in water.
4. A heterogeneous mixture forms because sucrose molecules are too large.
5. A homogeneous solution forms, and water is the solute.

Explanation: This question tests the skill of recognizing solubility of polar covalent compounds in water and distinguishing solvent from solute. Sucrose, a polar covalent solid, dissolves completely in water, a polar solvent, forming a clear, uniform solution due to hydrogen bonding interactions between sucrose molecules and water. With 1.0 g of sucrose in 20 mL of water, water is the solvent as it is the abundant liquid component. The clarity and uniformity indicate a homogeneous solution. A tempting distractor is choice A, which names sucrose as the solvent, stemming from the misconception that the solid is always the solvent irrespective of quantity. To evaluate dissolution, consider molecular polarity and intermolecular forces, and designate the solvent as the component in greater amount for proper classification.

Question 12

1. CO2 is the solvent because it is added using a gas tank.
2. Water is the solute because it is the liquid phase.
3. CO2 is the solute and water is the solvent in a homogeneous solution. (correct answer)
4. CO2 and water form a heterogeneous mixture because gases cannot dissolve in liquids.
5. CO2 is the solvent and water is the solute in a homogeneous solution.

Explanation: This question tests identification of solute and solvent when a gas dissolves in a liquid. When CO2 gas bubbles through water, some CO2 molecules dissolve in the water to form a homogeneous solution (carbonated water). In this solution, water is the solvent because it's the liquid medium doing the dissolving, while CO2 is the solute because it's the substance being dissolved. Choice D incorrectly claims gases cannot dissolve in liquids, when in fact many gases have measurable solubility in liquids (think of oxygen dissolved in water for fish to breathe). Remember that the physical state doesn't determine solvent/solute roles - the solvent is the dissolving medium (usually in greater amount) and the solute is what gets dissolved.

Question 13

1. A heterogeneous mixture forms because ionic compounds do not dissolve in water.
2. A homogeneous solution forms, with water as the solvent and NaCl as the solute. (correct answer)
3. A homogeneous solution forms, with NaCl as the solvent and water as the solute.
4. Two liquid layers form because water and NaCl are immiscible.
5. A homogeneous solution forms only if the mixture is heated to boiling.

Explanation: This question tests understanding of solution formation and identification of solute and solvent. When NaCl is added to water, the ionic compound dissolves because water molecules surround and separate the Na+ and Cl- ions through ion-dipole interactions. The resulting mixture is homogeneous (uniform throughout), with water as the solvent (the component in greater amount that does the dissolving) and NaCl as the solute (the substance being dissolved). Choice A incorrectly claims ionic compounds don't dissolve in water, when in fact many ionic compounds are highly soluble in water due to favorable ion-dipole interactions. When identifying solutions, remember that the solvent is typically the component present in greater amount and the solute is what gets dissolved.

Question 14

1. A homogeneous solution forms because stirring breaks CaCl2 into atoms that dissolve.
2. A homogeneous solution forms because CaCl2 is ionic and therefore dissolves in any liquid.
3. A homogeneous solution forms, with CaCl2 as the solvent and oil as the solute.
4. A heterogeneous mixture results because CaCl2 does not dissolve well in nonpolar oil. (correct answer)
5. Two layers form because CaCl2 is less dense than oil.

Explanation: This question tests understanding of solubility based on polarity differences. Calcium chloride (CaCl2) is an ionic compound that requires a polar solvent to dissolve, while vegetable oil is nonpolar. The ionic CaCl2 cannot dissolve in nonpolar oil because oil molecules cannot provide the strong ion-dipole interactions needed to separate Ca2+ and Cl- ions from the crystal lattice. Choice A incorrectly suggests ionic compounds dissolve in any liquid, when they specifically require polar solvents to provide ion-dipole interactions. When predicting ionic compound solubility, remember they need polar solvents - nonpolar solvents cannot overcome the strong ionic attractions in the crystal.

Question 15

1. Little dissolves, so the mixture is not a uniform solution because I2 is nonpolar. (correct answer)
2. Two liquid layers form because I2 is a liquid at room temperature.
3. A homogeneous solution forms because all solids dissolve in water if stirred long enough.
4. I2 dissolves completely because it can form ionic bonds with water.
5. A homogeneous solution forms readily because I2 is polar and water is polar.

Explanation: This question tests understanding of solubility based on polarity matching. Iodine (I2) is a nonpolar molecule because the two iodine atoms share electrons equally, while water is polar. Following "like dissolves like," nonpolar I2 has very limited solubility in polar water because water molecules prefer to hydrogen bond with each other rather than interact with nonpolar I2. Choice A incorrectly claims I2 is polar - diatomic molecules of the same element are always nonpolar due to equal electron sharing. To predict solubility, always consider the polarity match between solute and solvent - significant polarity differences lead to poor solubility.

Question 16

1. A homogeneous solution forms because polar dye particles disperse in polar water. (correct answer)
2. A heterogeneous mixture forms because colored solutions are suspensions.
3. Two layers form because dyes are always nonpolar.
4. A homogeneous solution forms, with dye as the solvent because it has stronger color.
5. No mixture forms because liquids cannot dissolve in liquids.

Explanation: This question tests understanding of solution formation with polar substances. Food coloring consists of polar dye molecules that readily dissolve in polar water through dipole-dipole interactions and/or hydrogen bonding, creating a homogeneous solution where the dye is uniformly distributed throughout the water. The color spreads evenly because individual dye molecules disperse at the molecular level, not as suspended particles. Choice B incorrectly claims colored solutions are suspensions - true solutions have solute particles at the molecular/ionic level, while suspensions have much larger particles that would eventually settle. To distinguish solutions from suspensions, remember that true solutions are transparent (though possibly colored) and don't settle over time.

Question 17

1. A homogeneous solution forms, with oil as the solvent and water as the solute.
2. A homogeneous solution forms, with water as the solvent and oil as the solute.
3. A heterogeneous mixture forms because the substances are immiscible and do not form one phase. (correct answer)
4. A homogeneous solution forms because stirring always produces a solution.
5. A heterogeneous mixture forms, with the less dense liquid always being the solute.

Explanation: This question tests understanding of immiscibility and heterogeneous mixture formation between polar and nonpolar liquids. Vegetable oil (nonpolar) and water (polar) are immiscible because they cannot form favorable intermolecular interactions with each other. The oil droplets and eventual layer formation indicate a heterogeneous mixture with two distinct phases - no homogeneous solution forms. The separation occurs because water molecules hydrogen bond strongly with each other, excluding the nonpolar oil molecules, while oil molecules cluster together through London dispersion forces. Choice D incorrectly suggests that stirring always produces a solution, but mechanical mixing cannot overcome the fundamental incompatibility between polar and nonpolar molecules. When mixing polar and nonpolar liquids, expect phase separation and heterogeneous mixture formation, with the less dense liquid (usually the nonpolar one) forming the top layer.

Question 18

1. A homogeneous solution forms, with water as the solvent and NaCl as the solute. (correct answer)
2. A homogeneous solution forms, with NaCl as the solvent and water as the solute.
3. A heterogeneous mixture forms because ionic compounds do not dissolve in polar solvents.
4. A heterogeneous mixture forms because stirring cannot break ionic bonds in NaCl.
5. A homogeneous solution forms, with NaCl and water present in equal amounts as co-solvents.

Explanation: This question tests the ability to identify solvent and solute in a solution formed by dissolving an ionic compound in water. When NaCl dissolves in water, it forms a homogeneous solution where the ionic solid dissociates into Na+ and Cl- ions that are uniformly distributed throughout the water. Water is the solvent because it is present in the larger amount (100 mL) and is the substance doing the dissolving, while NaCl is the solute because it is the substance being dissolved (2.0 g). The polar water molecules surround and stabilize the separated ions through ion-dipole interactions. Choice C incorrectly states that ionic compounds don't dissolve in polar solvents, when in fact the opposite is true - ionic compounds generally dissolve well in polar solvents due to favorable ion-dipole interactions. To identify solvent and solute, remember that the solvent is typically the component present in greater amount and the medium in which dissolution occurs.

Question 19

1. A homogeneous solution forms; acetic acid is the solvent and water is the solute.
2. A heterogeneous mixture forms; water is the solvent and acetic acid is the solute.
3. A homogeneous solution forms; water is the solvent and acetic acid is the solute. (correct answer)
4. A homogeneous solution forms; both are solutes because both are liquids.
5. A heterogeneous mixture forms; acetic acid is the solvent because it is an acid.

Explanation: This question tests the skill of identifying solvent and solute in miscible liquid mixtures based on relative amounts. Acetic acid (5.0 mL) mixes completely with water (95.0 mL) to form a clear, homogeneous solution because both are polar and can form hydrogen bonds. Water is the solvent as it is present in much greater volume, while acetic acid is the solute. The resulting vinegar-like mixture is uniform, confirming miscibility. A tempting distractor is choice A, which reverses solvent and solute, based on the misconception that the added component is always the solvent regardless of quantity. In liquid-liquid mixtures, always designate the component in larger amount as the solvent and verify miscibility through polarity to ensure correct identification.

Question 20

1. A heterogeneous mixture forms because molecular solutes do not dissolve in molecular solvents.
2. A homogeneous solution forms, with hexane as the solvent and iodine as the solute. (correct answer)
3. A heterogeneous mixture forms because hexane is nonpolar and cannot dissolve any solute.
4. A homogeneous solution forms, with iodine as the solvent and hexane as the solute.
5. A homogeneous solution forms only if the solute is ionic, so no solution forms here.

Explanation: This question tests the application of "like dissolves like" for nonpolar substances. Iodine (I2) is a nonpolar molecular solid, and hexane (C6H14) is a nonpolar liquid solvent, so they are compatible and form a homogeneous solution. The nonpolar I2 molecules dissolve readily in hexane through London dispersion forces, creating a purple solution. Hexane is the solvent because it's the liquid medium present in larger amount (50 mL), while iodine is the solute being dissolved (1.0 g). Choice A incorrectly claims that molecular solutes don't dissolve in molecular solvents, when compatibility actually depends on matching polarities, not molecular versus ionic character. Remember that nonpolar solutes dissolve well in nonpolar solvents through dispersion forces.