Stoichiometry If you had some eggs, flour, and sugar lying around the house and you wanted to make a cake, what would you do? How much cake could you make with the ingredients you already have? If you had to make 5 cakes, what would you do? How much material (eggs, flour, sugar) do you need to make 5 cakes?

Stoichiometry -Atoms are neither created nor destroyed in a chemical reaction. -It is possible to calculate the mass of any one of the products or of any one of the reactants if the mass of just one reactant or product is known using a balanced equation. -the coefficients in the balanced chemical equation are mole quantities, not masses.

Stoichiometry 2 H2 + O2 → 2 H2O Ex: Given the equation above, how many grams of water will be obtained by combining 5.0 grams of hydrogen gas with an excess of oxygen gas? mass  mass known  known  unknown  unknown mass moles moles mass Example Setup: Mole Ratio (always present)

Stoichiometry Other ways of doing stoichiometry: mass  moles known mass  known moles  unknown moles moles  mass known moles  unknown moles  unknown mass

known moles  unknown moles Stoichiometry moles  moles known moles  unknown moles