Stoichiometry I Mole-Mole

+ What is Stoichiometry? The word stoichiometry derives from two Greek words: stoicheion (meaning "element") and metron (meaning "measure"). +

What you Should Expect… The most common stoichiometric problem will present you with a certain amount of a reactant and then ask how much of a product can be formed.

Why do we use stoichiometry? Chemists use stoichiometry to determine quantities of chemicals needed, and to predict the quantities that will be produced for any chemical reaction.

Without stoichiometry we would not know the ratios in which chemicals react or how much product they will produce.

Mole Ratios You will always use a mole ratio when working stoichiometry problems. A mole ratio is a fraction that relates the amount of moles of any two substances in a chemical reaction.

Mole Ratios Express the ratio of moles in an equation using the coefficients: Ex. 2H2 + O2 2H2O What is the mole ratio between H2 and O2? 2mol H2 or 1mol O2 1mol O2 2mol H2

Mole Ratios What is the mole ratio between H2 and H2O? Ex. 2H2 + O2 2H2O 2mol H2 or 2mol H2O 2mol H20 2mol H2

2O3 3O2 What is the mole ratio between O3 and O2? 3mol O2 or 2mol O3 2mol O3 3mol O2

What are the mole ratios in this balanced equation? 3Ca + 2H3PO4 Ca3(PO4)2 + 3H2

Mole to Mole Problems: Write correct chemical formulas Write and balance the equation Convert everything to moles (sometimes it is already in moles) Use mole ratio to solve for what you are trying to find Convert everything into the required unit (if needed).

For Example Ca(OH)2 + HCl CaCl2 + H2O How many moles of calcium chloride will be produced if you start with 5 moles of HCl? Ca(OH)2 + HCl CaCl2 + H2O