Stoichiometry Chapter 9

Do Now Balance the equation Al + HCl → H 2 + AlCl 3 1.How many moles of HCl are required to produce 2 moles of AlCl 3 ? 2.How many moles of H 2 can be produced from 2 moles of Al? 3.List all other mole ratios that can be found from this equation.

Vocabulary Mole ratio- A conversion factor that relates the amount of moles of any two substances involved in a chemical reaction All reaction stoichiometry must start with a balanced chemical equation.

Reaction Stoichiometry Reaction stoichiometry problems can be classified by the information given in the problem: The information that is given (known) The information that you are expected to find (unknown) Three types of reactions are mole to mole, mole to mass, and mass to mass.

Practice How many moles of sodium will react with water to produce 4.0 mol of hydrogen in the following reaction? 2Na(s) + 2H 2 O(l) → 2NaOH(aq) + H 2 (g) Given: Wanted: 4 mol hydrogen Moles of sodium Mole to mole calculation /reaction

Practice Phosphorus burns in air to produce a phosphorus oxide in the following reaction: 4P(s) + 5O 2 (g) → P 2 O 5 (s) What mass of phosphorus will be needed to produce 3.25 mol of P 2 O 5 ? Given: Wanted: 3.25 mol of P 2 O 5 ? Mass of phosphorus Mole to mass calculation /reaction

Practice Calculate the mass of silver bromide produced from 22.5 g of silver nitrate in the following reaction. 2AgNO 3 (aq) + MgBr 2 → 2AgBr(s) + Mg(NO 3 ) 2 (aq) Given: Wanted: 22.5 g silver nitrate Mass of silver bromide Mass to mass calculation /reaction

Mole to Mole Conversions Al+ HCl → H 2 + AlCl 3 How many moles of H 2 can be produced from 11.6 mol of HCl? Given: Wanted: 11.6 mol HCl Moles of H 2

Practice How many moles of lithium chloride will be formed by the reaction of chlorine with mol of lithium bromide in the following reaction? 2LiBr(aq) + Cl 2 (g) → 2LiCl (aq) + Br 2 (l)

Practice Aluminum will react with sulfuric acid in the following reaction. 2Al(s) + 3H 2 SO 4 (l) → Al 2 (SO 4 ) 3 (aq) + 3H 2 (g) How many moles of H 2 SO 4 will react with 18 mol Al?

Practice Propane burns in excess oxygen according to the following reaction. C 3 H 8 + 5O 2 → 3CO 2 + 4H 2 O How many moles of CO 2 are formed from 3.85 mol of propane?

Stop and Think Why is the mole ratio so important in stoichiometrical calculations?

Practice In a spacecraft, the carbon dioxide exhaled by astronauts can be removed by its reaction with lithium hydroxide, LiOH, according to the following chemical equation. CO 2 (g) + 2LiOH(s) → Li 2 CO 3 (s) + H 2 O(l) How many moles of lithium hydroxide are required to react with 20 mol CO 2, the average amount exhaled by a person each day?

Practice Ammonia, NH 3, is widely used as a fertilizer and in many household cleaners. How many moles of ammonia are produced when 6 mol of hydrogen gas react with an excess of nitrogen gas? How many mol of nitrogen gas are required to produce 5 mol NH 3 ?

Practice The decomposition of potassium chlorate, KClO 3, into KCl and O 2 is used as a source of oxygen in the laboratory. How many moles of potassium chlorate are needed to produce 15 mol of oxygen gas?

Do Now Given this equation: N H 2 ---> 2 NH 3, write the following molar ratios: a)N 2 / H 2 b) N 2 / NH 3 c) H 2 / NH 3

Practice Answer the following questions for this equation: 2 H 2 + O 2 ---> 2 H 2 O a)What is the H 2 / H 2 O molar ratio? b) Suppose you had 20 moles of H 2 on hand and plenty of O 2, how many moles of H 2 O could you make? c) What is the O 2 / H 2 O molar ratio? d) Suppose you had 20 moles of O 2 and enough H 2, how many moles of H 2 O could you make?

Do Now Use this equation: N H 2 ---> 2 NH 3, for the following problems a)If you used 1 mole of N 2, how many moles of NH 3 could be produced? b) If 10 moles of NH 3 were produced, how many moles of N 2 would be required? c) If 3.00 moles of H 2 were used, how many moles of NH 3 would be made? d) If moles of NH 3 were produced, how many moles of H 2 are required?

Mole to Mass 1.Start with what you were given 2.Determine what is wanted 3.Determine your molar ratios 4.Use mole ratio to convert from one substance to another 5.Convert from moles to mass

Practice Phosphorus burns in air to produce phosphorus oxide in the following reaction: 4P (s) + 5 O 2 (g) → P 4 O 10 (s) a.What mass of phosphorus will be needed to produce 3.25 mol of P 4 O 10 ? b.If mol of phosphorus burns, what mass of oxygen is used? c.What mass of P 4 O 10 is produced?

Practice Hydrogen peroxide breaks down, releasing oxygen, in the following reaction. 2H 2 O 2 (aq) → 2H 2 O(l) + O 2 (g) a.What mass of oxygen is produced when mol of H 2 O 2 decompose? b.What mass of water is produced when 5.0 mol O 2 is produced by this reaction?

Stoichiometry: Mole to Mass Homework Page 890 in your textbook, #

Do Now Mg(s) + 2HCl(aq)  MgCl 2 (aq) + H 2 (g) a.How many grams of HCl are consumed by the reaction of 2.50 moles of magnesium? a.What is the mass in grams of H 2 gas when 4.0 moles of HCl is added to the reaction?

Mass to Mass 1.Start with what you were given 1.Determine what is wanted 2.Determine your molar ratios 3.Convert from mass to mole 4.Use mole ratio to convert from one substance to another 5.Convert from moles to mass

Practice Calculate the mass of silver bromide produced from 22.5 g of silver nitrate in the following reaction. 2AgNO 3 (aq) + MgBr 2 (aq) → 2AgBr(s) + Mg(NO 3 ) 2 (aq)

Practice What mass of acetylene, C 2 H 2, will be produced from the reaction of 90g of calcium carbide, CaC 2, with water in the following reaction? CaC 2 (s) + 2 H 2 0(l) → C 2 H 2 (g) + Ca(OH) 2 (s)

Stoichiometry: Mass to Mass homework Page 890 in your textbook, # 175