Question

Students are studying how two substances react. The students mix substance 1 with substance 2 in a solution. Later the students boil the solution, releasing substance 1 as a gas and leaving substance 2 as a solid. What type of change is described in the paragraph above? How do you know?

This is a chemical change, because the two substances were mixed together.


This is a chemical change, because the two substances were separated chemically by boiling.


This is a physical change, because the two substances were separated physically by boiling.


This is a chemical change, because a gas was released.

Answer 1

This is a chemical change, because a gas was released.

One of the substances must have evolved the gas and changed into something else (a chemical change).

Mixing two substances and separating them by boiling are physical changes.