Question

section review

1. a. what is the main difference between physical properties and chemical properties?

b. give an example of each.

1. classify each of the following as either a physical change or a chemical change.

a. tearing a sheet of paper
b. melting a piece of wax
c. burning a log

1. you are given a sample of matter to examine. how do you decide whether the sample is a solid, liquid, or gas?
2. contrast mixtures with pure substances.

Explanation:

1. a. Physical properties can be observed or measured without changing the substance's identity. Chemical properties describe a substance's ability to change into other substances.
2. b. An example of a physical property is color (e.g., the color of copper is reddish - brown). An example of a chemical property is flammability (e.g., wood is flammable).
3. a. Tearing a sheet of paper is a physical change as it only changes the physical form, not the chemical composition.
4. b. Melting a piece of wax is a physical change because it is a phase change from solid to liquid without altering the chemical makeup of the wax.
5. c. Burning a log is a chemical change since it involves a chemical reaction with oxygen, producing new substances like carbon dioxide and ash.
6. Observe the sample's shape and volume. A solid has a definite shape and volume. A liquid has a definite volume but takes the shape of its container. A gas has no definite shape or volume and fills the entire container.
7. A pure substance has a fixed composition and distinct properties. A mixture is composed of two or more substances physically combined, and its composition can vary.

Answer:

1. a. Physical properties don't change substance identity; chemical properties do.
2. b. Physical: color; Chemical: flammability.
3. a. Physical change.
4. b. Physical change.
5. c. Chemical change.
6. Observe shape and volume.
7. Pure substance has fixed composition; mixture has variable composition.