Science Common Sense

1310 - What is the law of conservation of mass in a chemical reaction.

The law of conservation of mass in a chemical reaction is simple: 'Matter can't be created or destroyed, only changed.'

Imagine you have a set of LEGO blocks. You can use those blocks to build a castle, then break the castle down and use the same blocks to build a car. The number of LEGO blocks remains the same. You just rearranged them.

In a chemical reaction, it's the same. The atoms (the building blocks of matter) get rearranged to form new substances, but the total number of atoms doesn't change. You can't create new atoms or make them disappear. So the mass (or weight) of the atoms before the reaction is equal to the mass of the atoms after the reaction. That's the law of conservation of mass!