Table of contents

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

1. Matter and Measurements

Physical & Chemical Changes

GOB Chemistry

1. Matter and Measurements

Physical & Chemical Changes

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2:28 minutes

Problem 80a

Textbook Question

Identify each of the following as a physical or chemical change:
a. Aspirin tablets are broken in half.

Verified step by step guidance

Step 1: Understand the difference between physical and chemical changes. A physical change involves a change in the physical state or appearance of a substance without altering its chemical composition. Examples include changes in shape, size, or state (e.g., melting, freezing). A chemical change, on the other hand, involves a transformation that changes the chemical composition of the substance, often producing new substances (e.g., rusting, burning).

Step 2: Analyze the given scenario. Breaking an aspirin tablet in half involves changing its size and shape, but the chemical composition of the aspirin remains unchanged.

Step 3: Determine whether the change is physical or chemical. Since the chemical structure of the aspirin is not altered and no new substances are formed, this is a physical change.

Step 4: Confirm your reasoning. Breaking the tablet does not involve any chemical reaction, such as a change in bonds or the formation of new compounds, which further supports that this is a physical change.

Step 5: Conclude that breaking an aspirin tablet in half is a physical change because it only affects the physical appearance (size and shape) of the tablet without altering its chemical composition.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Physical Change

A physical change involves a transformation that does not alter the chemical composition of a substance. Examples include changes in state, shape, or size, such as breaking, dissolving, or melting. In the case of aspirin tablets being broken in half, the tablets remain chemically the same; only their physical form is altered.

Chemical Change

A chemical change results in the formation of one or more new substances with different chemical properties. This process often involves a chemical reaction, where bonds between atoms are broken and formed. Unlike physical changes, chemical changes are usually irreversible under normal conditions, such as burning or rusting.

Distinguishing Changes

To distinguish between physical and chemical changes, one can assess whether the substance's identity remains intact. If the change can be reversed and the original substance can be recovered, it is likely a physical change. Conversely, if new substances are produced and the original cannot be easily restored, it indicates a chemical change.

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