Stoichiometry

Stoichiometry The study of the amount of substances consumed and produced in a chemical reaction.

Balanced Equations Show a Ratio of Moles The coefficients of a balanced equation give us the mole ratio. 2H2 + O2  2H2O 2 mol H2 reacts with 1 mol O2 to produce 2 mol H2O.

Using the Mole Ratio: Mole-Mole Stoichiometry N2 + 3H2  2 NH3 How many moles of hydrogen are needed to prepare 312 moles of ammonia? 312 moles NH3 3 moles H2 = 468 mol H2 2 moles NH3 Mole Ratio from Balanced Equation!

Mole to Mole Conversions 4 C2H5Cl + 13 O2 → 8 CO2 + 10 H2O + 2 Cl2 How many moles of Cl2 will be produced if 0.7339 moles of CO2 are also produced? 0.1835 moles

Mass to Mole Conversions If the given quantity is in grams, you must first convert the grams to moles using the molar mass. The ratio shown by the coefficients is in moles, not grams!

Mass to Mole Conversions 6.50 g of Al reacts with an excess of oxygen according to the following equation: 4 Al + 3 O2 → 2 Al2O3 How many moles of Al2O3 are formed? 6.50 g Al 1 mole Al 2 moles Al2O3 = 0.120 mol Al2O3 4 moles Al 26.98 g Al Change g to moles in order to use the mole ration of the equation.

Mass to Mole Conversions 2 NaOH + H2SO4  2 H2O + Na2SO4 How many moles of sodium sulfate will be formed if you start with 225 grams of sodium hydroxide and an excess of sulfuric acid? 2.81 moles

Mole to Mass Conversions If the given quantity is in moles, but the answer needs to be expressed in grams, use the mole ratio first. Then, use the molar mass to convert the moles of unknown to grams.

Mole to Mass Conversions How many grams of KCl is produced from 35 moles of K and excess Cl2 according to the following equation: 2 K + Cl2 → 2 KCl 35 mol K 2 mol KCl 74.55 g KCl = 2600 g KCl 2 mol K 1 mol KCl Change mol to g after converting from given to unknown.

Mole to Mass Conversions 2 NaClO3  2 NaCl + 3 O2 How many grams of O2 will be produced if 12.0 moles of NaClO3 react? 576 g

Mass to Mass Conversions If the given quantity is in grams, and the answer needs to be expressed in grams… Use 3-step dimensional analysis. First, use the molar mass of the given to convert the grams of given to moles. Then, use the mole ratio from the equation to convert from moles of given to moles of unknown. Finally, use the molar mass of the unknown to convert from moles of unknown to grams.

Mass to Mass Conversions Given the following equation: Cu + 2 Ag NO3  Cu(NO3)2 + 2 Ag If 89.5 g of Ag were produced, how many grams of Cu reacted? 89.5 g Ag 1 mol Ag 1 mol Cu 63.55 g Cu 107.9 g Ag 2 mol Ag 1 mol Cu = 26.4 g Cu

Mass to Mass Conversions Na2O + H2O  2 NaOH How many grams of NaOH will be produced from 125 grams of Na2O? 161 g