Question

When water is heated, bubbles form in the water. Is this evidence of a chemical reaction? Why?

a. Yes, the formation of a gas is evidence of a chemical reaction.
b. No, boiling water is a physical change.
c. No, the formation of gas bubbles is a secondary chemical reaction which is ignored.
d. Yes, the formation of a gas is proof a new compound has been made.
e. none of the above

Answer 1

Answer: Option (b) is the correct answer.

Step-by-step explanation:

A change that does not lead to any difference in chemical composition of a substance is known as a physical change.

For example, shape, size, mass, volume, density, boiling point, etc of a substance are all physical properties.

Boiling of water is a physical change as it leads to conversion of liquid state of water into vapor state.

On the other hand, changes that lead to bring change in chemical composition of a substance is known as a chemical change.

For example, exploding dynamite, rotting cheese etc are all chemical changes.

Thus, we can conclude that the statement no, boiling water is a physical change is true when water is heated, bubbles form in the water. This evidence is not of a chemical reaction.