1. how does the principle of conservation of mass relate to chemical reactions? 2. what information does a chemical equation give you?

1. According to the law of conservation of mass, in an isolated system, mass is neither created nor destructed by the physical conversions or chemical reactions. It is on the basis of the law of conservation of mass that in a chemical reaction, the mass of the products must be equivalent to the mass of the reactants.  

2. A chemical equation tells us about the phenomenon of conservation of mass, that is, atoms are neither created nor destroyed at the time of a chemical reaction. A balanced chemical equation tells us that which substances are the products and what substances are the reactants, and what proportion of each substance are taking part, as well as their association with each other, and the steps that take place at the time of a reaction.