Chem: when mass changes

Question

Explain what it means for mass to change.

Answer 1

A change in mass means a change in the amount of matter. This is different from a change in weight. Weight involves the force of gravity, whereas mass does not.

Also, I’d refer you to https://www.wyzant.com/resources/answers/712699/chem-change-in-mass

Answer 2

Generally, for the types of situations you encounter in normal conditions, you have to either take material away or add material for mass to change. In other words, in a closed system, there are no changes to mass.

Mass can change form from one element to another in a closed system but the overall mass is always the same.

So, if mass does change, then you can say that the system you are considering must be an open system (allowing mass to escape or to enter)