What is a balanced chemical equation? How would you use the law of conservation of mass to explain why a chemical equation must be balanced?
In every chemical equation that has ever been performed, mass is CONSERVED. What does this mean?
Conservation of mass means that if I start with 10 g of reactant, from all sources, at MOST I can get 10 g of product. In practice, I am not even going to get that, because losses inevitably occur on handling. Since mass is a property of atoms and molecules, fundamental particles in other words, it follows that these masses are conserved during a chemical reaction.
Let's examine a simple(?) combustion reaction, that of pentane:
Is this balanced? How do you know? If it is balanced, then there is mass equivalence of reactants,
Note that we practise stoichiometry all the time, For instance when we make a cash or electronic transaction; debits and credits are balanced. If they are not, someone will very soon notice.