Educational worksheet on physical and chemical changes and properties, featuring exercises to identify examples of each type of change and classify properties.

Problem Analysis:

The worksheet focuses on distinguishing between physical changes and chemical changes, as well as identifying whether certain properties are intensive or extensive. Let's solve each section step by step.

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Section A: Physical Change vs. Chemical Change

#### Definitions:
- Physical Change: A change in which the physical form of a substance is altered, but its chemical composition remains the same.
- Chemical Change: A change in which the chemical composition of a substance is altered, resulting in the formation of new substances.

#### Questions and Solutions:
1. Butter melts
- Explanation: Melting is a phase change where butter transitions from solid to liquid. No new substances are formed; only the state of matter changes.
- Answer: Physical Change

2. Sugar turns brown when heated
- Explanation: When sugar is heated, it undergoes caramelization, which involves breaking down sugar molecules and forming new compounds (e.g., carbon). This is a chemical reaction.
- Answer: Chemical Change

3. Silver tarnishes
- Explanation: Tarnishing occurs when silver reacts with sulfur-containing gases in the air to form silver sulfide. This is a chemical reaction that alters the chemical composition of the silver.
- Answer: Chemical Change

4. A white solid dissolves in vinegar, and bubbles form
- Explanation: Dissolving a white solid in vinegar (acetic acid) often involves a chemical reaction, such as the reaction of a carbonate or bicarbonate with acid to produce carbon dioxide gas (bubbles).
- Answer: Chemical Change

5. Milk spoils
- Explanation: Spoiling of milk involves the growth of bacteria and the breakdown of milk proteins and sugars into other compounds. This is a chemical change.
- Answer: Chemical Change

#### Final Answers for Section A:
| Event | Physical Change | Chemical Change |
|---------------------------|-----------------|-----------------|
| Butter melts | X | |
| Sugar turns brown when heated | | X |
| Silver tarnishes | | X |
| A white solid dissolves in vinegar, and bubbles form | | X |
| Milk spoils | | X |

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Section B: Identify Physical or Chemical Change

#### Questions and Solutions:
1. A piece of ice melts
- Explanation: Melting is a phase change where ice (solid water) becomes liquid water. The chemical composition remains H₂O.
- Answer: Physical Change

2. Mixing salt and pepper
- Explanation: Mixing salt and pepper combines two substances physically without altering their chemical compositions.
- Answer: Physical Change

3. Gasoline ignites
- Explanation: Ignition of gasoline involves combustion, where gasoline reacts with oxygen to produce carbon dioxide, water, and energy. This is a chemical change.
- Answer: Chemical Change

4. A marshmallow is toasted over a campfire
- Explanation: Toasting a marshmallow involves heating, which can cause caramelization (a chemical reaction) and charring (formation of carbon). This is a chemical change.
- Answer: Chemical Change

5. A marshmallow is cut into half
- Explanation: Cutting a marshmallow changes its shape but does not alter its chemical composition.
- Answer: Physical Change

#### Final Answers for Section B:
1. Physical Change
2. Physical Change
3. Chemical Change
4. Chemical Change
5. Physical Change

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Section C: Intensive vs. Extensive Properties

#### Definitions:
- Intensive Property: A property that does not depend on the amount of substance present (e.g., density, color, melting point).
- Extensive Property: A property that depends on the amount of substance present (e.g., mass, volume).

#### Questions and Solutions:
1. Pressure
- Explanation: Pressure is an intensive property because it does not depend on the amount of substance. For example, the pressure in a container of gas is the same regardless of how much gas is present.
- Answer: Intensive

2. Mass
- Explanation: Mass is an extensive property because it depends on the amount of substance. Doubling the amount of a substance doubles its mass.
- Answer: Extensive

3. Volume
- Explanation: Volume is an extensive property because it depends on the amount of substance. Doubling the amount of a substance generally doubles its volume.
- Answer: Extensive

4. Color
- Explanation: Color is an intensive property because it does not depend on the amount of substance. For example, the color of a solution remains the same regardless of how much of the solution is present.
- Answer: Intensive

5. Melting point
- Explanation: Melting point is an intensive property because it does not depend on the amount of substance. The melting point of a substance is the same regardless of how much of it is present.
- Answer: Intensive

#### Final Answers for Section C:
| Property | Intensive or Extensive? |
|---------------|-------------------------|
| Pressure | Intensive |
| Mass | Extensive |
| Volume | Extensive |
| Color | Intensive |
| Melting point | Intensive |

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Final Answer Summary:

- Section A:
| Event | Physical Change | Chemical Change |
|---------------------------|-----------------|-----------------|
| Butter melts | X | |
| Sugar turns brown when heated | | X |
| Silver tarnishes | | X |
| A white solid dissolves in vinegar, and bubbles form | | X |
| Milk spoils | | X |

- Section B:
1. Physical Change
2. Physical Change
3. Chemical Change
4. Chemical Change
5. Physical Change

- Section C:
| Property | Intensive or Extensive? |
|---------------|-------------------------|
| Pressure | Intensive |
| Mass | Extensive |
| Volume | Extensive |
| Color | Intensive |
| Melting point | Intensive |

Boxed Final Answer:
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\text{See detailed solutions above.}
}
\]