Question

chemical properties of matter – understanding how substances react
section a: comprehension

1. define chemical property in your own words. (2 points)
2. how are chemical properties different from physical properties? (4 points)
3. list four chemical properties mentioned in the article and give one real - life example for each. (8 points)

a.
b.
c.
d.

1. what are three pieces of evidence that a chemical change has taken place? (6 points)

Explanation:

1. A chemical property is a characteristic of a substance that can be observed during a chemical reaction, where the substance changes into a different substance.
2. Physical properties can be observed or measured without changing the identity of the substance (e.g., color, melting - point), while chemical properties involve a change in the substance's identity through a chemical reaction.
3. Common chemical properties and examples:

• Flammability: Wood burning in a fire.
• Reactivity with oxygen: Iron rusting when exposed to air (oxygen).
• Reactivity with acids: Zinc reacting with hydrochloric acid to produce hydrogen gas.
• Toxicity: Cyanide being toxic to living organisms.

1. Three pieces of evidence of a chemical change are: production of a gas (e.g., bubbles when vinegar and baking - soda react), formation of a precipitate (e.g., when silver nitrate and sodium chloride react to form silver chloride precipitate), and change in color (e.g., when an apple turns brown due to oxidation).

Answer:

1. A characteristic of a substance shown during a chemical reaction where it becomes a different substance.
2. Physical properties can be observed without changing the substance's identity; chemical properties involve a change in identity.

3.
a. Flammability; Wood burning.
b. Reactivity with oxygen; Iron rusting.
c. Reactivity with acids; Zinc reacting with HCl.
d. Toxicity; Cyanide being toxic.

1. Production of a gas, formation of a precipitate, change in color.