Quiz El chemistry. 1

Question 1

observation

Answer 1

orderly, direct information gathered about a phenomenon

Question 2

physical change

Answer 2

change in a substance that does not change its composition

Question 3

phase change

Answer 3

a transition of matter from one state to another

Question 4

chemical change

Answer 4

when one or more substances change into a new substance

Question 5

law of conservation of mass

Answer 5

states that mass is neither created nor destroyed during a chemical reaction

Question 6

Describe how iron turns into a brownish-red powder. Name the reactants and product that are involved.

Answer 6

Iron reacts with oxygen in the air to form rust. The reactants are iron and oxygen. The product is rust.

Question 7

Define chemical change

Answer 7

A chemical change is the change of one or more substances into new substances.

Question 8

Describe the results of a physical change and list three examples of physical change.

Answer 8

During a physical change, a substance is changed, but its composition does not change. Examples will vary but might include changes such as melting, freezing, boiling, bending, and tearing.

Question 9

Describe the results of a chemical change. List four indicators of chemical change.

Answer 9

During a chemical change, the composition of a substance is altered. Possible indicators of chemical change include a change in color, odor, or temperature, and the formation of a gas or solid from a liquid.

Question 10

Evaluate A friend tells you, “Because composition does not change during a physical change, the appearance of a substance does not change.” Is your friend correct? Explain.

Answer 10

The statement is incorrect. While the composition does not change, a change in appearance often accompanies a physical change.