UNIT 1 Chemical Reactions Part II Workbook Name: 1
Molar Volume 1. How many moles of a gas will occupy 2.50 L at STP? 2. Calculate the volume that 0.881 mol of gas at STP will occupy. 3. Determine the volume of a container that holds 2.4 mol of gas at STP. 4. How many moles of air are in a 6.06 L tire at STP? 5. Calculate the volume that 3.60 g H 2 gas will occupy at STP. Bonus: What is the molar mass of a pure gas that has a density of 1.40 g/l at STP? Hint: use the units to help you determine the correct ratio. 2
Percent Composition Find the percent composition of the following compounds: 1. CuSO 4 2. HNO 3 3. H 2 SO 4 4. Cu(OH) 2 5. C 12 H 22 O 11 6. aspartame, C 14 H 18 N 2 O 5 3
Empirical and Molecular Formulas Find the empirical or molecular formula for the following questions 1. If a compound has a composition of 40.0% carbon, 6.714% hydrogen, and 53.29% oxygen, determine the empirical formula of the compound. 2. Experimental analysis determined that a compound contained 7.30g of sodium, 5.08g of sulphur, and 7.62g of oxygen. What is the empirical formula for this compound? 3. Analyses of a compound shows 31.1% Fe, 15.56% N, and 53.33% O. What is the empirical formula? 4
4. A compound has the following composition: 19.3% Na, 26.9% S and 53.8% O. What is the empirical formula? If the molecular mass is 238g/mol, what is the molecular formula? 5. If a compound contains 71.65% chlorine, 24.27% carbon, and 4.07% hydrogen, determine the molecular formula if the molar mass is 98.96g/mol. 6. A compound consists of Fe and Cl. The total mass of the compound is 34.04g. 15g of the compound is Fe. Calculate the empirical formula for the compound. 7. 24 g of C combine with 6g of H to make a chemical compound. Calculate the empirical formula for the compound. If the molar mass of the compound is 30g/mol, calculate the molecular formula. 5
Mole to Mole Stoichiometry 1. How many moles of hydrogen are needed to completely react with two moles of nitrogen? N 2 + 3H 2 2NH 3 2. How many moles of oxygen are produced by the decomposition of six moles of potassium chlorate? 2KClO 3 2KCl + 3O 2 3. How many moles of hydrogen are produced from the reaction of three moles of zinc with an excess of hydrochloric acid? Zn + 2HCl ZnCl 2 + H 2 4. How many moles of oxygen are necessary to react completely with four moles of propane (C3H8)? C 3 H 8 + 5O 2 3CO 2 + 4H 2 O 5. How many moles of potassium nitrate are produced when two moles of potassium phosphate react with two moles of aluminum nitrate? K 3 PO 4 + Al(NO 3 ) 3 3KNO 3 + AlPO 6
6. How many moles of magnesium are required to react with 2.0 mol of hydrochloric acid? The equations for this reaction is Mg + 2HCl MgCl 2 + H 2 7. Aluminum reacts with HCl to produce aluminum chloride (AlCl 3 ) and hydrogen gas. Write a balanced equation for the reaction and calculate the number of moles of HCl required to react with 0.87 mol of Al. 8. Glucose (C 6 H 12 O 6 ) combines with O 2 in the body to produce carbon dioxide and water. Write a balanced equation for this reaction. How many moles of O 2 are required to combine with 0.25 mol of glucose? How many moles of CO 2 and H 2 O would be produced in this reaction? 9. Calcium carbonate (CaCO 3 ) combines with HCl to produce calcium chloride (CaCl 2 ), water, and carbon dioxide gas. Write the balanced equation for this reaction. How many moles of HCl are required to react with 2.5 mol of CaCO 3? How many moles of CO 2 would be produced? 10. Zinc reacts with H 2 SO 4 to yield ZnSO 4 and hydrogen gas. How many moles of hydrogen will be produced if 0.36 mol of zinc react with an equal amount of H 2 SO 4? 7
Mass to Mass Stoichiometry 11. If 80.0 grams of O 2 are reacted in the following reaction, how many grams of N 2 O will be produced? 2 NH 3 + 2 O 2 N 2 O + 3 H 2 O 12. Given 145.7 grams of manganese (IV) oxide, how much hydrochloric acid (HCl) is needed to use up the MnO 2 completely? MnO 2 + 4 HCl Cl 2 + MnCl 2 + 2 H 2 O 13. How many grams of carbon are needed to completely react with 125 g of iron (III) oxide? Fe 2 O 3 + 3 C 2 Fe + 3 CO 14. If you react 100 grams of aluminum chloride with excess calcium, how many grams of calcium chloride are produced? 3 Ca + 2 AlCl 3 3 CaCl 2 + 2 Al 15. How many grams of carbon dioxide will form from the combustion of 320.0 grams of C 5 H 12 with excess oxygen? C 5 H 12 + 8 O 2 5 CO 2 + 6 H 2 O 16. Given 75.0 grams of iron (IV) sulfide, how many grams of sulfur dioxide are produced? 4 FeS 2 + 11 O 2 2 Fe 2 O 3 + 8 SO 2 8
Limiting Reactants Complete the following. 1. The equation for the complete combustion of ethane (C 2 H 4 ) is C 2 H 4(g) + 3O2 2 CO 2(g) + 2H2O(g). If 2.70 mole C2H4 is reacted with 6.30 mole, identify the limiting reactant. 2. Hydrogen gas can be produced by the reaction of magnesium metal with hydrochloric acid. Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g). Identify the limiting reactant when 6.00 g HCl reacts with 5.00 g Mg. In each of the following questions, identify the limiting factor, the excess reactant, and then calculate the amount of indicated product that is formed from the amounts given. 1. Given 3.0 moles of methane and 4.0 moles of oxygen gas, calculate the moles of carbon dioxide gas produced. Calculate the moles of excess reactant that remains. CH 4 + 2 O 2 CO 2 + 2 H 2 O 2. Given 5.0 mol of acetylene and 11.0 mol of oxygen gas, calculate the moles of CO 2 gas produced. Calculate the moles of excess reactant that remains. 2 C 2 H 2 + 5 O 2 4 CO 2 + 2 H 2 O 9
3. Given 5.0 mol of sulphur and 8.4 mol of oxygen gas, calculate the mass of SO 3 gas produced. Calculate the moles of excess reactant that remains. 2 S + 3 O 2 2 SO 3 4. Given 0.16 g of hydrogen gas and 5.6 g of nitrogen gas, calculate the mass of HN 3 produced. Calculate the mass of excess reactant that remains. H 2 + 3 N 2 2 HN 3 5. According to the reaction below, AlBr 3 + Cl 2 Br 2 + AlCl 3 How many grams of aluminum chloride is produced from 82.0 g of chlorine and 175.0 g of aluminum bromide. How many grams of the excess reactant remains? 10
Theoretical and Percent Yield 1. When 5.00 g of KClO 3 is heated it decomposes according to the equation: 2 KClO 3 2 KCl + 3 O 2 a. Calculate the theoretical yield of oxygen. b. Give the percent yield if 1.78 g of O 2 is produced. c. How much O 2 would be produced if the percent yield was 78.5%? 2. What is the percent yield of NH 3 if 40.5 g NH 3 is produced from 20.0 mol H 2 and excess N 2? 3. The electrolysis of water forms H 2 and O 2. What is the percent yield of O 2 if 12.3 g of O 2 is produced from the decomposition of 14.0 g H 2 O? 11
4. 107 g of oxygen is produced by heating 300 grams of potassium chlorate. Calculate the percent yield of oxygen. 2KClO 3 2KCI + 3O 2 5. What is the percent yield of iron (II) sulphide if 3.00 moles of Fe reacts with excess sulphur to produce 220 grams of iron (II) sulphide? Fe + S FeS 6. Iron pyrites (FeS 2 ) reacts with oxygen according to the following equation: 4 FeS 2 + 11 O 2 2 Fe 2 O 3 + 8 SO 2. is If 300 g of iron pyrites is burned in 200 g of O 2, 143 grams of iron (III) oxide produced. What is the percent yield of iron (III) oxide? 7. 2 H 2 + O 2 2 H 2 O. What is the percent yield of H 2 O if 58 g H 2 O are produced by combining 60 g O 2 and 7.0 g H 2? *Hint: find the limiting reactant* 12