Understanding Chemical Reactions

What is a chemical reaction?

• A process where substances are mixed without changing properties

• A process in which new substances are formed with different properties

• A process where substances are heated without any change

• A process where substances are cooled without any change.

Fill in the blank: Properties of matter can be both ______ and recorded.

• ignored

• observed

• hidden

• forgotten

Which of the following is an example of a physical change?

• A) Burning wood

• B) Rusting iron

• C) Melting ice

• D) Baking a cake

Physical changes result in changes of ______.

• state

• substance

• atoms

• energy

Which process is NOT a physical change?

• Freezing

• Melting

• Dissolving

• Burning

True or False: Dissolving is always a physical change.

• True

• False

In a chemical reaction, atoms rearrange to form molecules with ______ properties.

• identical

• different

• similar

• unchanged

What is the role of professional chemists in solving unique problems?

• Combine substances

• Separate substances

• Destroy substances

• Ignore substances

Fill in the blank: The properties of each substance determine how it ______ with other substances.

• Interacts

• Reacts

• Combines

• Separates

Fill in the blank: The same number of atoms are present before and after the chemical reaction, but new substances have been formed into ______.

• A) Products

• B) Reactants

• C) Elements

• D) Compounds