Evidence of Chemical Reactions

Question 1

The images show two unrelated events occurring at separate times. Which event is most likely an example of a chemical reaction?

Revolt · Accepted Answer

Event 1 because there is a color change.

Question 2

Which indicator most likely suggests that a chemical change is taking place?

Revolt · Accepted Answer

change of color

Question 3

Two different liquids are mixed together. Which observation indicates that an exothermic chemical reaction has taken place?

Revolt · Accepted Answer

a rise in temperature

Question 4

Which statement describes a chemical reaction?

Revolt · Accepted Answer

Atoms in the reactants are rearranged to form new substances.

Question 5

When sodium metal is added to water, an orange flame is observed on the metal surface. Based on this observation, what can best be concluded?

Revolt · Accepted Answer

A chemical reaction occurs because heat and light are given off.

Question 6

Which is the most important question for deciding if a chemical reaction has occurred?

Revolt · Accepted Answer

Was any heat energy given off?

Question 7

Burning a piece of wood in fire can be best described as a

Revolt · Accepted Answer

chemical change because the atoms in wood and oxygen are rearranged.

Question 8

Which term best describes the role of hydrogen gas in the formation of a water molecule?

Revolt · Accepted Answer

reactant

Question 9

A piece of limestone erodes due to acid rain. This process can be best described as a

Revolt · Accepted Answer

slow chemical change.

Question 10

During an experiment, a student observes the formation of a precipitate. Why does this indicate that a chemical reaction is likely occurring?

Revolt · Accepted Answer

A solid forms, and there is a change of color.

Evidence of Chemical Reactions Answers