Physical and Chemical Properties and Changes worksheet for students to classify properties and changes.

Let's solve each part of this worksheet step by step and explain the reasoning behind each answer.

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1. Classify the following as physical or chemical by putting an X.

| Property | Physical | Chemical |
|--------|---------|--------|
| Red color | X | |
| Solubility | X | |
| Density | X | |
| Supports combustion | | X |
| Reacts with acid to form H₂ | | X |

Explanation:

- Red color: This is a physical property because it describes appearance without changing the substance’s identity.
- Solubility: How well a substance dissolves in a solvent — this is a physical property (no new substance formed).
- Density: Mass per unit volume — a physical property, measurable without changing composition.
- Supports combustion: This refers to the ability to burn, which involves a chemical reaction (oxidation), so it’s a chemical property.
- Reacts with acid to form H₂: This indicates a chemical reaction (e.g., metals like zinc reacting with HCl), so it’s a chemical property.

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2. Classify the following properties as physical or chemical. If it is chemical, put a 'C' next to it; if it is intensive physical, put an 'I'; if extensive physical, put an 'E'.

| Property | C, E, or I? |
|--------|------------|
| Color | I |
| Mass | E |
| Flammability | C |
| Density | I |
| Reacts with acid to form hydrogen gas | C |

Explanation:

- Color: Intensive physical property – doesn't depend on amount, and can be observed without changing substance.
- Mass: Extensive physical property – depends on the amount of matter.
- Flammability: Chemical property – relates to how a substance reacts (burns) with oxygen.
- Density: Intensive physical property – same for a given substance regardless of sample size.
- Reacts with acid to form hydrogen gas: Chemical property – involves a chemical reaction producing a new substance (H₂).

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3. Identify the following as physical (P) or chemical (C) changes.

| Change | Type |
|-------|------|
| i. NaCl (table salt) dissolves in water | P |
| ii. Ag (silver) tarnishes | C |
| iii. An apple is cut | P |
| iv. Heat changes water to steam | P |
| v. Baking soda reacts with vinegar | C |
| vi. Milk sours | C |
| vii. Sugar dissolves in water | P |
| viii. Wood rots | C |
| ix. Pancakes cook | C |
| x. Grass grows | C |

Explanation:

- i. NaCl dissolves in water: Physical change – the salt breaks apart into ions but no new substances are formed; it can be reversed by evaporation.
- ii. Silver tarnishes: Chemical change – silver reacts with sulfur in air to form silver sulfide (a new compound).
- iii. An apple is cut: Physical change – only shape changes; no new substance formed.
- iv. Water to steam: Physical change – phase change from liquid to gas; molecules remain H₂O.
- v. Baking soda + vinegar: Chemical change – produces CO₂ gas, water, and sodium acetate (new substances).
- vi. Milk sours: Chemical change – bacteria convert lactose to lactic acid, altering the composition.
- vii. Sugar dissolves in water: Physical change – sugar molecules disperse but remain intact; reversible.
- viii. Wood rots: Chemical change – decomposition by fungi/bacteria, breaking down cellulose into simpler compounds.
- ix. Pancakes cook: Chemical change – proteins denature, starches caramelize, Maillard reaction occurs.
- x. Grass grows: Chemical change – involves photosynthesis, where CO₂ and H₂O are converted into glucose and O₂ (new substances).

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✔ Final Answers:

#### 1.
| Property | Physical | Chemical |
|--------|---------|--------|
| Red color | X | |
| Solubility | X | |
| Density | X | |
| Supports combustion | | X |
| Reacts with acid to form H₂ | | X |

#### 2.
| Property | C, E, or I? |
|--------|------------|
| Color | I |
| Mass | E |
| Flammability | C |
| Density | I |
| Reacts with acid to form hydrogen gas | C |

#### 3.
- i. P
- ii. C
- iii. P
- iv. P
- v. C
- vi. C
- vii. P
- viii. C
- ix. C
- x. C

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This worksheet helps distinguish between physical and chemical properties and changes, emphasizing whether a substance’s identity changes. Physical changes involve state or form, while chemical changes produce new substances.