Question

How can you detect that a chemical reaction has occurred? Select all that apply.

A precipitate has formed.
A color change has occurred.
A gas has formed.
A phase change has occurred.
A temperature change occurred.

Answer 1

A color change has occurred.

A temperature change occurred.

A precipitate has formed.

A gas has formed

Answer 2

All, except for "a phase change occured". That would be a physical change. Say for example we had an ice cube (solid). and it melts into water. It becomes a liquid. However, it is still water. Although the phase changed, it's composition did not change.