Matter Changes Exploration Worksheet - Answer Key

For Teacher Use

Science experiment with chemical and physical changes

🔬 Part 1: Answer Key

1. Physical and Chemical Changes:

a) Ice melting into water: PHYSICAL

b) Baking soda and vinegar producing bubbles: CHEMICAL

c) Tearing a piece of paper: PHYSICAL

d) A candle burning and producing smoke: CHEMICAL

2. Three signs of chemical change:

a) Color change

b) Gas production (bubbling)

c) Temperature change

Also acceptable: odor/smell change, formation of a precipitate, light production

3. Vocabulary matching:

Physical Change → Change in size, shape, or state with no new substance

Chemical Change → Atoms rearrange to form new substances

Reactants → Starting materials in a chemical reaction

Products → New substances formed in a chemical reaction

🧪 Part 2: Answer Key

4. Ice melting explanation:

This is a physical change because the ice is only changing from solid to liquid state. The water molecules remain the same - no new substance is formed. The change is reversible because the water can freeze back into ice.

5. Vinegar and baking soda evidence:

The evidence includes: 1) Gas production (bubbling/fizzing), 2) Temperature change (container gets cooler), and 3) New substances are formed (carbon dioxide gas, water, and sodium acetate). These signs indicate that atoms have rearranged to form new substances.

6. Fill in the blanks:

In a physical change, the atoms and molecules stay the same, and the change is usually reversible. In a chemical change, a new substance is formed.

📖 Part 3: Answer Key

7. Main idea:

Plastics are made from natural resources through chemical changes

8. Meaning of "synthetic":

Synthetic means artificially made or manufactured, not naturally occurring. Synthetic materials are created by humans through chemical processes rather than found in nature.

9. Cause and effect relationship:

Cause: Plastics are the result of chemical changes

Effect: They don't break down easily in nature, causing environmental concerns

Also acceptable: Cause - Chemical processes transform natural resources; Effect - New substances with different properties are created