Unit 8 Solutions Study Guide Answer Key

CONCEPT 1: Types of Solutions

Vocabulary

  • Heterogeneous mixture: Mixture with an uneven distribution throughout.

  • Suspension: Heterogeneous mixture with particles so large they settle out unless constantly stirred.

  • Colloid: Heterogeneous mixture appearing homogeneous; particles are slightly larger than in a solution and can be identified by the Tyndall effect.

  • Tyndall effect: Light is scattered by colloidal particles dispersed in a transparent medium.

  • Homogeneous mixture: Mixture with an even distribution throughout.

  • Solution: Homogeneous mixture of 2 or more substances uniformly dispersed.

  • Solute: Substance that is dissolved.

  • Solvent: Substance doing the dissolving; the dissolving medium.

  • Immiscible: Liquids not soluble in each other, forming separate layers when mixed.

  • Miscible: Liquids that dissolve freely in one another in any proportion.

  • Solubility: A measure of how well one substance dissolves in another.

  • Soluble: Capable of being dissolved.

  • Hydrates: Ionic substances that form crystals with water molecules.

  • Electrolyte: Ionic substance that dissolves in water to create a solution that can conduct electricity.

  • Strong electrolyte: Compound whose aqueous solutions conduct electricity well due to nearly all of the dissolved compound being in ion form.

  • Weak electrolyte: Compound whose aqueous solutions conduct electricity poorly due to only a small amount of the dissolved compound being in ion form.

  • Nonelectrolyte: Substance that dissolves in water creating a solution that cannot conduct electric current.

  • Solubility curve: Graph showing the amount of solute a solvent can dissolve at different temperatures.

  • Henry’s Law: The solubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid.

Objectives

  1. Distinguish Between Homogeneous and Heterogeneous Mixtures Using Particle Diagrams

    • Homogeneous mixture: Uniform distribution of particles.

    • Heterogeneous mixture: Non-uniform distribution of particles.

  2. Examples of Solutions (Identifying Solute and Solvent)

    • Soda: CO2CO_2 (gas) is the solute dissolved in water (solvent).

    • Lemonade: Powder is the solute dissolved in water (solvent).

    • Brass: Zinc is the solute dissolved in copper (solvent).

  3. Differentiate Between Solutions, Colloids, and Suspensions

    SOLUTIONS

    COLLOIDS

    SUSPENSIONS

    Homogeneous/Heterogeneous?

    Homogeneous

    Heterogeneous

    Heterogeneous

    Particle size

    Smallest

    Intermediate

    Largest

    Particles settle out?

    Do not settle out

    Do not settle out

    Settle out

    Separated by filtration?

    No

    No

    Yes

    Scatter light (Tyndall effect)?

    No

    Yes

    Sometimes

  4. Explain Why Water is Considered the Universal Solvent

    • Water's polarity allows it to have attractive forces that pull ions apart and molecules out of a substance when dissolving.

    • It is liquid at room temperature.

  5. **Real-World Example of

CONCEPT 1: Types of Solutions

Vocabulary

  • Heterogeneous mixture: Mixture with an uneven distribution throughout. Examples include salad dressing, gravel, and chunky soup. The different components are easily visible.

  • Suspension: Heterogeneous mixture with particles so large they settle out unless constantly stirred. Examples include muddy water and blood. Particles can be filtered out.

  • Colloid: Heterogeneous mixture appearing homogeneous; particles are slightly larger than in a solution and can be identified by the Tyndall effect. Examples include milk, fog, and gelatin. Particles do not settle out.

  • Tyndall effect: Light is scattered by colloidal particles dispersed in a transparent medium. Used to distinguish between colloids and solutions.

  • Homogeneous mixture: Mixture with an even distribution throughout. Examples include air, sugar dissolved in water, and vinegar. Components are not easily visible.

  • Solution: Homogeneous mixture of 2 or more substances uniformly dispersed. Can exist in any phase (gas, liquid, solid).

  • Solute: Substance that is dissolved. Examples include sugar in sugar water and salt in saltwater.

  • Solvent: Substance doing the dissolving; the dissolving medium. Examples include water in sugar water and water in saltwater.

  • Immiscible: Liquids not soluble in each other, forming separate layers when mixed. Examples include oil and water.

  • Miscible: Liquids that dissolve freely in one another in any proportion. Examples include ethanol and water.

  • Solubility: A measure of how well one substance dissolves in another. Influenced by temperature and pressure.

  • Soluble: Capable of being dissolved. For example, sugar is soluble in water.

  • Hydrates: Ionic substances that form crystals with water molecules. For example, CuSO<em>4⋅5H</em>2OCuSO<em>4 \cdot 5H</em>2O is a hydrate of copper sulfate.

  • Electrolyte: Ionic substance that dissolves in water to create a solution that can conduct electricity. Essential for nerve and muscle function.

  • Strong electrolyte: Compound whose aqueous solutions conduct electricity well due to nearly all of the dissolved compound being in ion form. Examples include NaClNaCl, HClHCl, and KOHKOH.

  • Weak electrolyte: Compound whose aqueous solutions conduct electricity poorly due to only a small amount of the dissolved compound being in ion form. Examples include acetic acid and ammonia.

  • Nonelectrolyte: Substance that dissolves in water creating a solution that cannot conduct electric current. Examples include sugar and ethanol.

  • Solubility curve: Graph showing the amount of solute a solvent can dissolve at different temperatures. Used to determine the saturation of a solution.

  • Henry’s Law: The solubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid. Important in understanding carbonated beverages and scuba diving.

Objectives

  1. Distinguish Between Homogeneous and Heterogeneous Mixtures Using Particle Diagrams

    • Homogeneous mixture: Uniform distribution of particles. Particle diagrams show evenly spaced particles of solute and solvent.

    • Heterogeneous mixture: Non-uniform distribution of particles. Particle diagrams show clumps or uneven spacing of particles.

  1. Examples of Solutions (Identifying Solute and Solvent)

    • Soda: CO2CO_2 (gas) is the solute dissolved in water (solvent).

    • Lemonade: Powder (sugar, citric acid, flavorings) is the solute dissolved in water (solvent).

    • Brass: Zinc is the solute dissolved in copper (solvent).

  1. Differentiate Between Solutions, Colloids, and Suspensions

    SOLUTIONS

    COLLOIDS

    SUSPENSIONS

    Homogeneous/Heterogeneous?

    Homogeneous

    Heterogeneous

    Heterogeneous

    Particle size

    Smallest (less than 1 nm)

    Intermediate (1-1000 nm)

    Largest (greater than 1000 nm)

    Particles settle out?

    Do not settle out

    Do not settle out

    Settle out

    Separated by filtration?

    No

    No (can be separated by ultracentrifugation)

    Yes

    Scatter light (Tyndall effect)?

    No

    Yes

    Sometimes

  2. Explain Why Water is Considered the Universal Solvent

    • Water's polarity (H2OH_2O) allows it to have attractive forces (hydrogen bonds) that pull ions apart and molecules out of a substance when dissolving. Oxygen is slightly negative and hydrogen is slightly positive, allowing water to interact with both positive and negative charges.

    • It is liquid at room temperature, making it a convenient solvent for many substances.

  1. Real-World Example of Solubility and Saturation

    • Sugar dissolving in water to make a saturated solution for making candy.