2.3. Changes in Matter http://www.ck12.org
Lesson Review Questions
Reviewing Concepts
- What is the main difference between a physical change and a chemical change?
- How must the chemical properties of a given substance be observed?
- Give an example of a situation where a color change occurs, but not because of a chemical reaction.
Problems
- Classify the following as physical properties or chemical properties of the element nickel.
a. It is gray in color.
b. It melts at 1455°C.
c. It reacts with sulfuric acid.
d. It is a conductor of electricity.
e. It forms a compound with oxygen. - Combustion, also called burning, is a reaction with oxygen gas. When propane is combusted, carbon dioxide
and water are formed. Identify the reactants and the products of this combustion reaction. - Classify each of the following as a chemical change or a physical change.
a. Sugar dissolves in water.
b. A peach rots.
c. Icicles melt in the warm sunlight.
d. A baking cake rises in the oven.
e. A leaf changes its color in the fall.
f. Food coloring is added to a glass of water. - Describe clues that you might observe during the following situations that would indicate that a chemical
reaction is likely occurring.
a. A log burns in the fireplace.
b. A mixture of baking soda and vinegar fizzes.
c. A silver fork tarnishes.
d. A plumbing pipe becomes clogged with lime.
Points to Consider
A chemist must do more than simply make observations about chemical changes that are occurring in his or her
experiments. He or she must also take measurements in order to fully understand what is taking place during
chemical reactions.
- What types of measurements are routinely made by chemists?
- How does a chemist indicate the degree of confidence in a measurement?
- How are different numerical measurements manipulated when performing calculations?