The conservation of mass is an important idea in science. It tells us that in a closed system, the total weight of the starting materials (reactants) is the same as the total weight of the ending materials (products).

Here’s what that means for predicting results in experiments:

• It helps keep the mass balanced in chemical equations.
• It shows that even though reactants change during a reaction, they don’t just vanish.

For example, let’s say we have a reaction where 2 grams of hydrogen combines with 16 grams of oxygen.

The total weight (18 grams) stays the same when we make water.

So, in simple terms, we can write it like this:

Starting materials (Reactants):

• 2 g of Hydrogen (H)
• 16 g of Oxygen (O)

Ending material (Product):

• 18 g of Water (H₂O)

This shows that the mass before and after the reaction remains equal.