Physical And Chemical Changes And Properties Of Matter Worksheet ... - Free Printable

Problem Analysis:

The task involves identifying whether the given statements describe chemical changes, physical changes, or physical properties. Let's break this down step by step:

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#### Definitions:
1. Chemical Change (Chemical Property):
- A chemical change occurs when a substance is transformed into one or more new substances with different chemical compositions.
- Examples: Burning wood, rusting iron, baking bread.

2. Physical Change (Physical Property):
- A physical change involves a change in the state or form of a substance without altering its chemical composition.
- Examples: Melting ice, boiling water, tearing paper.

3. Physical Property:
- A physical property describes the characteristics of a substance that can be observed or measured without changing its chemical identity.
- Examples: Color, density, melting point, hardness.

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#### Task Instructions:
- Identify whether each statement on the left corresponds to a chemical change, physical change, or physical property.
- Use the provided answer key to match the correct category.

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Solution:

#### Statements and Their Categories:
1. Fluorescent conductivity
- This is a physical property because it describes a characteristic of a material (how well it conducts electricity under fluorescent light) without altering its chemical composition.
- Answer: Physical property

2. Burning wood
- This is a chemical change because burning wood produces new substances like ash, carbon dioxide, and water vapor. The original wood is chemically transformed.
- Answer: Chemical change

3. Melting candle wax
- This is a physical change because the wax changes from a solid to a liquid state without forming new substances. The chemical composition remains the same.
- Answer: Physical change

4. Length of metal object
- This is a physical property because it describes a measurable characteristic of the metal object without altering its chemical identity.
- Answer: Physical property

5. Rusting of metal
- This is a chemical change because rusting involves the reaction of metal with oxygen and moisture to form iron oxide, a new substance.
- Answer: Chemical change

6. Boiling water
- This is a physical change because boiling water changes from a liquid to a gas (water vapor) without forming new substances. The chemical composition remains the same.
- Answer: Physical change

7. Enzymatic hydrolysis
- This is a chemical change because enzymatic hydrolysis breaks down complex molecules (e.g., starch into glucose) into simpler substances through a biochemical reaction.
- Answer: Chemical change

8. Conductivity
- This is a physical property because it describes how well a material allows electric current to pass through it without altering its chemical composition.
- Answer: Physical property

9. Washing clothes
- This is a physical change because washing clothes typically involves removing dirt and stains without creating new substances. The chemical composition of the clothes remains unchanged.
- Answer: Physical change

10. Welding two metals together
- This is a physical change because welding involves heating and fusing metals together, but no new chemical substances are formed. The metals remain chemically the same.
- Answer: Physical change

11. Tearing paper
- This is a physical change because tearing paper alters its shape and structure but does not change its chemical composition.
- Answer: Physical change

12. Burning gasoline
- This is a chemical change because burning gasoline produces new substances such as carbon dioxide, water vapor, and other combustion products. The gasoline is chemically transformed.
- Answer: Chemical change

13. Melting ice
- This is a physical change because melting ice changes its state from solid to liquid without altering its chemical composition.
- Answer: Physical change

14. Baking bread
- This is a chemical change because baking bread involves reactions that produce new substances, such as carbon dioxide gas, which causes the bread to rise. The flour and other ingredients are chemically transformed.
- Answer: Chemical change

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#### Additional Questions:
15. A change in size or shape is a physical change.
- True: Changing size or shape does not alter the chemical composition of a substance.
- Answer: True

16. An example of a chemical change is white water foaming.
- False: White water foaming is a physical change because it involves the mixing of air and water without forming new substances.
- Answer: False

17. When a candle burns, this is a physical change because a change in odor does not mean a chemical change.
- False: Burning a candle is a chemical change because it produces new substances like carbon dioxide and water vapor. The change in odor is a result of the chemical reaction.
- Answer: False

18. When sugar dissolves in water, this is a physical change because the sugar is still present.
- True: Dissolving sugar in water is a physical change because the sugar molecules are dispersed in water but not chemically altered.
- Answer: True

19. When acids and bases mix, sodium chloride is produced and the temperature increases.
- True: Mixing acids and bases is a chemical change because new substances (like sodium chloride) are formed, and energy is released (temperature increase).
- Answer: True

20. Tasting a banana is a chemical change because it has grown too soft.
- False: Tasting a banana is a sensory experience and does not involve a chemical change. The softening of the banana may be due to ripening, which is a chemical process, but tasting itself is not a chemical change.
- Answer: False

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#### Identify the Following as a Physical or Chemical Change:
21. You have spilled your milk out in the rain and it turns sour.
- Chemical change: The milk turning sour involves bacterial activity that produces new substances, altering its chemical composition.
- Answer: Chemical change

22. You spill some oil on the floor.
- Physical change: Spilling oil does not alter its chemical composition; it simply changes its location.
- Answer: Physical change

23. Sucrose breaks down into water and hydrogen gas.
- Chemical change: Breaking sucrose into water and hydrogen gas involves a chemical reaction that produces new substances.
- Answer: Chemical change

24. You boil water.
- Physical change: Boiling water changes its state from liquid to gas but does not alter its chemical composition.
- Answer: Physical change

25. Tasting a banana because it has grown too soft.
- Chemical change: The softening of the banana is due to ripening, which involves chemical processes like the breakdown of starches into sugars.
- Answer: Chemical change

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#### Five Characteristics of a Chemical Change:
1. Color change: Often indicates the formation of new substances.
2. Formation of a solid called precipitate: New solids may form during chemical reactions.
3. The reaction is irreversible (difficult to reverse): Chemical changes usually cannot be undone easily.
4. Heat is absorbed or released: Chemical reactions often involve energy changes.
5. Bubbling and fizzing gas produced: Gas production is a common sign of chemical reactions.

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Final Answer:

\[
\boxed{
\begin{array}{ll}
1. & \text{Physical property} \\
2. & \text{Chemical change} \\
3. & \text{Physical change} \\
4. & \text{Physical property} \\
5. & \text{Chemical change} \\
6. & \text{Physical change} \\
7. & \text{Chemical change} \\
8. & \text{Physical property} \\
9. & \text{Physical change} \\
10. & \text{Physical change} \\
11. & \text{Physical change} \\
12. & \text{Chemical change} \\
13. & \text{Physical change} \\
14. & \text{Chemical change} \\
\end{array}
}
\]