Understanding mass conservation is really important for figuring out what will happen in chemical reactions.

The main idea is that in a closed system, the total weight of what you start with (the reactants) is the same as the total weight of what you end up with (the products).

We can sum it up like this:

• Weight of Reactants = Weight of Products

What Mass Conservation Means:

1. Balanced Equations: In chemistry, we need to make sure equations are balanced. This means that the number of atoms on one side of the equation should match the number on the other side.

   • For example, take this reaction:
     $2H_2 + O_2 \rightarrow 2H_2O$
   • Before the reaction, the total weight is 4 g from hydrogen (H) and 16 g from oxygen (O), making it 20 g.
   • After the reaction, we get water (H₂O), and its mass is also 20 g.

2. Stoichiometry: This is a big word, but it just means that we can use the weights of reactants to figure out how much product we will get.

   • For instance, if 10 g of substance A reacts with 9 g of substance B, then the total weight of the products must be 19 g.

3. Predicting Products: When we understand the weights of the reactants, we can accurately guess what the products will be. This is based on balanced equations and the amounts we have to start with.