It is firmly based on the law of conservation of mass. This important rule states that mass never simply disappears in a closed system. The total mass of your starting materials always equals the mass of your final products.
Stoichiometry relies on balanced chemical equations to find exact molar ratios. These numerical ratios act as handy conversion factors for the chemist. They let you calculate the exact amount of product that should theoretically form.
You can also figure out the precise starting amounts needed for a specific target goal. This math is vital when moving a reaction from a tiny lab flask to a massive factory. Mixing chemicals in their perfect molar ratios saves companies a lot of money.
It also prevents leftover harmful chemicals from becoming dangerous industrial waste. A very common student mistake is trying to do math without balancing the equation first. If the starting equation is wrong, every single calculation after it will fail.
Another major trap involves confusing raw chemical mass with moles. You must always convert starting grams into moles before looking at the equation ratios. Atoms react by counting them in moles, not by weighing them in grams.