1. How many moles of hydrogen are needed to completely react with 2.00 moles of nitrogen?

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1 Stoichiometry Mole-to-Mole 1. How many moles of hydrogen are needed to completely react with 2.00 moles of nitrogen? N 2 + H 2 NH 3 2. If 5.50 moles of calcium carbide (CaC 2 ) reacts with an excess of water, how many moles of acetylene (C 2 H 2 ), a gas used in welding, will be produced? CaC 2 + H 2 O Ca(OH) 2 + C 2 H 2 3. When an antacid tablet dissolves in water, the fizz is due to a reaction of sodium hydrogen carbonate and citric acid (H 3 C 6 O 5 H 7 ). How many moles of Na 3 C 6 O 5 H 7 will be produced if one tablet containing moles of sodium hydrogen carbonate is dissolved? NaHCO 3 + H 3 C 6 O 5 H 7 CO 2 + H 2 O + Na 3 C 6 O 5 H 7 4. How many moles of hydrogen are produced from the single replacement reaction of 3.50 moles of zinc with excess hydrochloric acid? 5. How many moles of oxygen are produced by the decomposition of 6.75 moles of potassium chlorate? 1

2 Stoichiometry Mole-to-Mass 1. The process of which an organic acid and an alcohol react to form an ester and water is known as esterification. Ethylbutanoate (C 3 H 7 COOC 2 H 5 ), an ester, is formed when the alcohol ethanol (C 2 H 5 OH) and butanoic acid (C 3 H 7 COOH) are heated in the presence of sulfuric acid. Determine the mass of ethyl butanoate produced if 4.50 mol of ethanol is used. C 2 H 5 OH + C 3 H 7 COOH C 3 H 7 COOC 2 H 5 + H 2 O 2. The exothermic reaction between liquid hydrazine (N 2 H 2 ) and liquid hydrogen peroxide (H 2 O 2 ) is used to fuel rockets. The products of this reaction are nitrogen gas and water. How much hydrazine, in moles, is needed to produce grams of nitrogen gas? N 2 H 2 + H 2 O 2 N 2 + H 2 O 3. Carbon dioxide is a greenhouse gas that is linked to global warming. It is released into the atmosphere through the combustion of octane (C 8 H 18 ) in gasoline. Write the balanced chemical equations for the combustion of octane and calculate the mass of octane needed to release 5.00 mol of CO A solution of potassium chromate reacts with a solution of lead (II) nitrate to produce a yellow precipitate of lead (II) chromate and a solution of potassium nitrate. Write the balanced chemical equation for this reaction and calculate the mass of lead chromate formed from the reaction of mol of potassium chromate. 2

3 Stoichiometry Mass-to-mass 1. If you start with grams of lithium hydroxide, how many grams of lithium bromide will be produced? LiOH + HBr LiBr + H 2 O 2. If you start with 45 grams of ethylene (C 2 H 4 ), how many grams of carbon dioxide will be produced? C 2 H 4 + O 2 CO 2 + H 2 O 3. If you start with 5.5 grams of Calcium chloride and excess lead (II) nitrate, how many grams of lead (II) chloride will be produced? 4. If you start with 20 grams of hydrochloric acid and excess sodium sulfate, how many grams of hydrogen sulfate will be produced? 3

4 Mass-to-mass 1. Ethanol (C 2 H 5 OH), also known as grain alcohol, can be made from the fermentation of sugar (C 6 H 12 O 6 ). Determine the mass of ethanol produced from 750 g of sugar. C 6 H 12 O 6 C 2 H 5 OH + CO 2 2. Chloroform (CHCl 3 ), an important solvent, is produced by a reaction between methane and chlorine. How much CH 4, in grams, is needed to produce 50.0 grams of CHCl 3? CH 4 + Cl 2 CHCl 3 + HCl 3. To extract gold from its ore, the ore is treated with sodium cyanide solution in the presence of oxygen and water. Determine the mass of gold that can be extracted if 25.0 g of sodium cyanide is used. Au + NaCN + O 2 + H 2 O NaAu(CN) 2 + NaOH 4. Gasohol is a mixture of ethanol and gasoline. Determine the mass of CO 2 produced from the combustion of g of ethanol (C 2 H 5 OH). 4

5 Stoichiometry Practice 1. Zinc reacts with hydrochloric acid to produce zinc chloride and hydrogen. How many moles of HCl are required to produce 7.50 moles of ZnCl 2? 2. Copper metal reacts with silver nitrate to form silver and copper(ii) nitrate. How many grams of copper are required to form 250 g of silver? 3. When aluminum is burned in excess oxygen, aluminum oxide is produced. How many grams of oxygen are required to produce 0.75 moles of Al 2 O 3? 4. How many grams of iron(iii) chloride are produced when 15.3 g of iron react with excess chlorine gas? 5. Iron metal reacts with lead (II) nitrate to form lead and iron (II) nitrate. How many moles of lead will be produced from 3.65 moles of lead (II) nitrate? 6. Aluminum reacts with hydrochloric acid to produce aluminum chloride and hydrogen gas. How many mol of HCl are required to react with g of aluminum? 5

6 7. How many grams of iron are needed to react with 31.0 L of chlorine gas at STP to produce iron(iii) chloride? 8. When 9.34 g of calcium react with excess sodium sulfate, how many grams of calcium sulfate will be produced? 9. How many liters of oxygen gas at STP are required to react with 65.3 g of aluminum in the production of aluminum oxide? 10. Magnesium reacts with nickel (II) nitrate to form nickel and magnesium nitrate. How many grams of magnesium are required to react with 0.40 mol of nickel (II) nitrate? 11. Nickel (II) nitrate and potassium carbonate react to form nickel (II) carbonate and potassium nitrate. How many mol of Ni(NO 3 ) 2 are needed to react 2.90 g of K 2 CO 3? 12. Zinc metal reacts with chromium(iii) nitrate in a single replacement reaction. How many grams of zinc are required to react with 0.11 mol of Cr(NO 3 ) 3? 6

7 Limiting Reactant 1. In 1901, Thomas Edison invented the nickel-iron battery. The following reaction takes place in the battery. How many mol of Fe(OH) 2 is produced when 5.00 mole of Fe and 8.00 mol of NiO(OH) react? Fe + NiO(OH) + H 2 O Fe(OH) 2 + Ni(OH) 2 2. One of the few xenon compounds that form is cesium xenon heptafluoride (CsXeF 7 ). How many moles of this compound can be produced from the reaction of 12.5 mol of cesium fluoride with 10.0 mol of xenon hexafluoride? CsF + XeF 6 CsXeF 7 3. Iron is obtained commercially by the reaction of hematite (Fe 2 O 3 ) with carbon monoxide. How many grams of iron is produced when 25.0 mol of hematite reacts with 30.0 mol of carbon monoxide? Fe 2 O 3 + CO Fe + CO 2 4. The reaction of chlorine gas with solid phosphorus (P 4 ) produces solid phosphorus pentachloride. When 16.0 g of chlorine reacts with 23.0 g of P 4, which reactant is limiting? Which reactant is in excess? 7

8 5. An alkaline battery produces electrical energy according to this equation. Determine the limiting reactant if 25.0 g of Zn and 30.0 g of MnO 2 are used. Then determine the mass of Zn(OH) 2 produced. Zn + MnO 2 + H 2 O Zn(OH) 2 + Mn 2 O moles of nitrogen gas reacts with 4.85 moles of hydrogen gas to form ammonia (NH 3 ). b. How many moles of ammonia will form? 7. A welder has 20.0 moles of acetylene gas (C 2 H 2 ) and 10.0 moles of oxygen gas. They combine to form water and carbon dioxide. a. Identify the limiting reactant. b. How many moles of carbon dioxide gas will form? 8. A student places 2.36 moles of acetic acid and 3.89 moles of sodium hydroxide in a beaker. They react to form sodium acetate and water. a. How many moles of water will form? 8

9 moles of bromine gas and moles of chlorine gas react to form tribromochlorine (Br 3 Cl). a. How many moles of this product will form? grams of sodium sulfate reacts with grams of barium nitrate in a double replacement reaction. a. How many grams of barium sulfate will form? grams of hydrogen gas reacts with 30.0 grams of oxygen gas to form water vapor. a. How many grams of water vapor will form? 12. Lithium reacts spontaneously with bromine to produce lithium bromide. Write the balanced chemical equation for this reaction. If 25.0 g of lithium and 25.0 g of bromine are present at the beginning of the reaction, determine a. The limiting reactant b. The mass of lithium bromide produced c. The mass of the excess reactant left 9

10 Limiting Reactant and Excess Reactant 1. How many moles of mercury II oxide will be produced when 2.7 moles of mercury are placed with 3.2 moles of oxygen? 2. How many grams of calcium bromide will be produced when 4.2 moles of iron III bromide are placed with 4.5 moles of calcium? a. How many moles of excess reactant remain after the reaction is over? 3. How many grams of iron III sulfate result when 1.85 g of iron are placed with 2.97 g of copper II sulfate? a. How many grams of excess reactant remain after the reaction is over? 4. How many liters of carbon dioxide are produced when 3.18 x molecules of butane (C 4 H 10 ) burn in 5.17 x molecules of oxygen? a. How many liters of excess reactant remain after the reaction? (Assume STP) 10

11 g of acetic acid reacts with 10.0 g of lead (II) hydroxide to form water and lead (II) acetate. a. Which reactant is in excess? b. How many grams of it will remain after the reaction goes to completion? How many grams of lead (II) acetate will form? g of magnesium reacts with 44.3 g of copper (II) nitrate to form copper and magnesium nitrate. a. What mass of copper will form? b. What mass of reactants will remain unreacted? 11

12 Limiting and Excess Reactants When 8.7 grams of aluminum reacts with 40.1 grams of hydrobromic acid, how many grams of H 2 are formed? b. For the reactant in excess, how many grams are left over at the end of the reaction? When 60.2 grams of silicon reacts with 49.4 grams of nitrogen gas, how many grams of Si 3 N 4 are formed? b. For the reactant in excess, how many grams are left over at the end of the reaction? When 75.0 grams of copper (II) chloride reacts with grams of potassium iodide, how many grams of solid iodine are formed? The other products are potassium chloride and copper (I) iodide. b. For the reactant in excess, how many grams are left over at the end of the reaction? When 89.5 grams of iron (II) sulfide reacts with 17.4 grams of oxygen gas, sulfur dioxide and iron (III) oxide are formed. a. How many grams of sulfur dioxide are formed? b. What is the limiting reactant? c. For the reactant in excess, how many grams are left over at the end of the reaction? 12

13 Limiting and Excess Reactants 1. When 30 grams of calcium nitrate and 50 grams of sodium phosphate undergo a double replacement reaction, b. What mass of calcium phosphate is produced? c. How many grams of excess reactant are left? 2. Assuming we start with 100 grams of potassium sulfate and 45 grams of calcium chlorate and they undergo a double replacement reaction, b. What mass of calcium sulfate is produced? c. How many grams of excess reactant are left? 13

14 3. Assuming we start with 15 grams of copper (II) chloride and 20 grams of silver nitrate and they undergo a double replacement reaction, b. What mass of copper (II) nitrate is produced? c. How many grams of excess reactant are left? 4. Assuming we start with 25.0 grams of lead (II) nitrate and 15.0 grams of sodium iodide and they undergo a double replacement reaction, b. What mass of lead (II) iodide is produced? c. How many grams of excess reactant are left? 14

15 Limiting Reactants 1. Given the organic combustion of propane (C 3 H 8 ), determine the following a. If you start with 14.8 g of C 3 H 8 and 3.44 g of oxygen, determine the limiting reactant b. determine the number of grams of H 2 O produced c. determine the number of grams of excess reactant left 2. Aluminum sulfite reacts with sodium hydroxide to form sodium sulfite and aluminum hydroxide. a. If 10.0 g of aluminum sulfite is reacted with 10.0 g of sodium hydroxide, determine the limiting reactant b. Determine the number of grams of sodium sulfite produced c. Determine the number of grams of excess reactant left over in the reaction 3. In a thermite reaction, iron (III) oxide and aluminum undergo a single displacement reaction. a. If 25.4 g of iron (III) oxide is reacted with 10.2 g of aluminum, determine the limiting reactant b. Determine the number of grams of aluminum oxide produced c. Determine the number of grams of excess reactant left over in the reaction 15

16 % Yield 1. Lead (II) oxide is obtained by roasting galena, lead (II) sulfide, in air. a. Balance the equation and determine the theoretical yield of PbO if g of PbS is heated. b. What is the percent yield if g of PbO is obtained? PbS(s) + O 2 (g) PbO(s) + SO 2 (g) 2. Upon heating, calcium carbonate decomposes to calcium oxide and carbon dioxide. a. Determine the theoretical yield of carbon dioxide if g of calcium carbonate is heated. b. What is the percent yield of carbon dioxide if 97.5 g of carbon dioxide is collected? 16

17 % Yield 1. If 20 grams of lithium hydroxide reacts with excess calcium chloride, what is my theoretical yield of lithium chloride? a. If 6 grams of lithium chloride is actually produced, what is my percent yield? 2. If I start with 5 grams of Propane (C 3 H 8 ) and it combusts in excess oxygen, what is my theoretical yield of water? a. I got a percent yield of 75% How many grams of water did I make? 3. In the reaction of barium with hydrochloric acid, my theoretical yield of barium chloride was 10.7 grams. If my actual yield was 4.5 grams, what was my percent yield? 4. Sodium oxide is produced when sodium chloride reacts with calcium oxide. What is my theoretical yield of sodium oxide if I start with 20 grams of calcium oxide? 5. What is my theoretical yield of iron (II) chloride if I start with 34 grams of iron (II) bromide that reacts with excess potassium chloride? a. What is my percent yield of iron (II) chloride if my actual yield is 4 grams? 17

18 6. What is my percent yield of titanium (II) oxide if I start with 20 grams of titanium (II) sulfide reacting in excess water and my actual yield of titanium (II) oxide is 12 grams? 7. What is my actual yield of uranium hexabromide if I start with 100 grams of uranium reacting in excess bromine and get a percent yield of 83%? grams of sulfuric acid decomposes and produces 7.1 grams of water, what is my percent yield? 18

19 Stoichiometry 1. If 25 grams of carbon dioxide is formed from the decomposition of sodium bicarbonate, a. What mass of sodium carbonate was formed? b. If 50.0 g of sodium carbonate is formed in the reaction, what is the percent yield? 2. If 15 grams of strontium chloride reacts with 20 grams of sodium sulfate, what mass of sodium chloride can be formed? b. How much of the excess reactant remains? c. If 10.3 g of sodium chloride is obtained in the reaction, what is the percent yield? 3. If 40 grams of magnesium reacts with 100 grams of nitric acid, what mass of hydrogen gas can be formed? b. How much of the excess reactant remains? c. If 1.4 g of hydrogen is formed in the reaction, what is the percent yield? 19

20 Stoichiometry Practice 1. Potassium superoxide, KO 2, is used in rebreathing masks to generate oxygen according to the reaction below. If the mask contains mol KO 2 and 1.80 g water, how many moles of oxygen can be produced? What is the limiting reactant? KO 2 (s) + H 2 O(l) KOH(s) + O 2 (g) 2. Suppose 13.7 g of C 2 H 2 reacts with 18.5 g O 2 according to the reaction below. How many mol of CO 2 is produced? What is the limiting reactant? C 2 H 2 (g) + O 2 (g) CO 2 (g) + H 2 O(l) 3. Nitrogen gas can react with hydrogen gas to form gaseous ammonia, NH 3. If 4.7 g of nitrogen reacts with 9.8 g of hydrogen, what mass of ammonia is formed? What is the limiting reactant? 4. Sulfur dioxide reacts with ozone (O 3 ) in the atmosphere to form gaseous sulfur trioxide and oxygen. The sulfur trioxide can then react with water to produce acid rain. In the initial reaction, if 5.13 g of sulfur dioxide reacts with 6.18 g of ozone, what mass of sulfur trioxide is formed? b. What mass of the excess reactant will be left? c. If 5.75 g of sulfur trioxide was obtained, what is the percent yield? 20

21 5. Another way that acid rain is formed in the atmosphere is when sulfur dioxide reacts with oxygen in a reaction catalyzed by dust in the atmosphere to form sulfur trioxide. If 7.99 g of sulfur dioxide reacts with 3.18 g of oxygen, how much sulfur trioxide can form? b. What mass of the excess reactant will be left? c. If g of sulfur trioxide was obtained, what is the percent yield? 6. Heating together the solids ammonium chloride and calcium hydroxide can generate ammonia, NH 3. Aqueous calcium chloride and liquid water are also formed. If a mixture of 33.0 g each of ammonium chloride and calcium hydroxide is heated, how many grams of NH 3 will form? b. What mass of the excess reactant will be left? c. If 9.25 g of ammonia was obtained, what is the percent yield? 7. Nitrogen monoxide is formed primarily in car engines, and it can react with oxygen to form gaseous nitrogen dioxide. Nitrogen dioxide forms another component of acid rain when it comes in contact with water. In the initial reaction, if 3.13 g of nitrogen monoxide reacts with 4.16 g of oxygen, how much nitrogen dioxide will form? b. What mass of the excess reactant will be left? c. If 2.95 g of nitrogen dioxide was obtained, what is the percent yield? 21