Student worksheet on solubility and temperature with completed answers.

Problem Overview:

The task involves understanding the concepts of solubility and temperature, specifically how temperature affects the dissolution of a solute in a solvent. The Gizmo simulation is used to explore these concepts with potassium nitrate as the solute and water as the solvent.

Solution and Explanation:

#### Prior Knowledge Questions:
1. What happens when you stir a spoonful of sugar into hot water?
- Answer: The sugar dissolves.
- Explanation: Stirring helps break down the sugar crystals and increases the rate at which sugar molecules disperse into the water. Hot water has higher kinetic energy, which facilitates faster dissolution.

2. When sugar or another substance is dissolved in water, it disappears from view and forms a homogeneous mixture with the water, also called a solution. If you can't see the sugar, how can you tell that it is there?
- Answer: Make the water evaporate by boiling it.
- Explanation: When water evaporates, the dissolved sugar remains behind as a solid residue, indicating its presence.

3. Does sugar dissolve more easily in hot water or cold water?
- Answer: Hot water.
- Explanation: Higher temperatures increase the kinetic energy of both the solute (sugar) and the solvent (water) molecules. This increased energy allows the sugar molecules to move more freely and interact with water molecules more effectively, leading to faster dissolution.

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#### Gizmo Warm-up:
The Gizmo simulation focuses on potassium nitrate as the solute and water as the solvent. The goal is to study how temperature affects solubility.

1. In this solution, what is the solute? What is the solvent?
- Solute: Potassium nitrate
- Solvent: Water
- Explanation: The solute is the substance being dissolved (potassium nitrate), and the solvent is the substance doing the dissolving (water).

2. Click Add 10 g to mix 10 g of potassium nitrate into the water.
- A. Did all of the potassium nitrate dissolve?
- Answer: Yes.
- Explanation: If all the potassium nitrate disappeared upon stirring, it indicates that it fully dissolved into the water.
- B. How can you tell?
- Answer: The potassium nitrate disappeared as it was stirred into the water.
- Explanation: A homogeneous mixture means the solute is evenly distributed throughout the solvent, and no undissolved particles are visible.

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Key Concepts:

- Solubility: The maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature.
- Temperature Effect: Generally, increasing the temperature increases the solubility of solids in liquids because higher temperatures provide more energy for molecular interactions.
- Homogeneous Mixture/Solution: A mixture where the solute is uniformly distributed in the solvent, resulting in a clear appearance.

Final Answer:

\boxed{
\text{1. Solute: Potassium nitrate, Solvent: Water} \\
\text{2. A. Yes, all of the potassium nitrate dissolved.} \\
\text{ B. The potassium nitrate disappeared as it was stirred into the water.}
}
**