Stoichiometry Practice Problems and Solutions

Stoichiometry Worksheet and Key 2 KClO3 è 2 KCl + 3 O2 1. How many moles of O2 will be formed from 1.65 moles of KClO3? 1.65 mol KClO3 mol O2 = mol O2 mol KClO3 2. How many moles of KClO3 are needed to make 3.50 moles of KCl? 3.50mol KCl = mol KClO3 3. How many moles of KCl will be formed from 2.73 moles of KClO3? = 4 Fe + 3 O2 è 2 Fe2O3 4. How many moles of Fe2O3 are produced when 0.275 moles of Fe is reacted? 0.275 mol Fe = mol Fe2O3 5. How many moles of Fe2O3 are produced when 31.0 moles of O2 is reacted? = 6. How many moles of O2 are needed to react with 8.9 moles of Fe? = 2 H 2 O è 2 H2 + O 2 7. How many moles of O2 are produced when 1.26 moles of H2O is reacted? 8. How many moles of H2O are needed to produce 55.7 moles of H2? 9. If enough H2O is reacted to produce 3.40 moles of H2, then how may moles of O2 must have been made? (a bit challenging, but just think about it and you can probably figure it out) 2 KClO3 è 2 KCl + 3 O2 10. How many grams of O2 will be formed from 3.76 grams of KClO3? 3.76g KClO3 1 mol KClO3 122.55 g KClO3 g O2 mol O2 mol KClO3 g O2 = mol O2 11. How many grams of KClO3 are needed to make 30.0 grams of KCl? 30.0 g KCl mol KCl mol KClO3 g KCl mol KCl g KClO3 = g KClO3 = g KCl = g Fe2O3 = g Fe2O3 mol KClO3 12. How many grams of KCl will be formed from 2.73 g of KClO3? 2.73 g KClO3 4 Fe + 3 O2 è 2 Fe2O3 13. How many grams of Fe2O3 are produced when 42.7 grams of Fe is reacted? 42.7 g Fe mol Fe g Fe mol Fe2O3 mol Fe g Fe2O3 mol Fe2O3 14. How many grams of Fe2O3 are produced when 17.0 grams of O2 is reacted? 17.0 g O2 15. How many grams of O2 are needed to react with 125 grams of Fe? = Some cars can use butane (C4H10) as fuel: 2 C4H10 + 13 O2 è 8 CO2 + 10 H2O 16. How many grams of CO2 are produced from the combustion of 100. grams of butane? 100. g C4H10 = g CO2 = g O2 17. How many grams of O2 are needed to react with of 100. grams of butane? 100. g C4H10 18 How many grams of H2O are produced when 5.38g of O2 is reacted? KEY 2 KClO3 è 2 KCl + 3 O2 1. How many moles of O2 will be formed from 1.65 moles of KClO3? 1.65 mol KClO3 3 mol O2 2 mol KClO3 = 2.48 mol O2 2. How many moles of KClO3 are needed to make 3.50 moles of KCl? 3.50 mol KCl 2 mol KClO3 2 mol KCl = 3.50 mol KClO3 3. How many moles of KCl will be formed from 2.73 moles of KClO3? 2.73 moles KClO3 2 mol KCl 2 mol KClO3 = 2.73 mol KCl 4 Fe + 3 O2 è 2 Fe2O3 4. How many moles of Fe2O3 are produced when 0.275 moles of Fe are reacted? 0.275 mol Fe 2 mol Fe2O3 4 mol Fe = 0.138 mol Fe2O3 5. How many moles of Fe2O3 are produced when 31.0 moles of O2 are reacted? 31.0 mol O2 2 mol Fe2O3 3 mol O2 = 20.7 mol Fe2O3 6. How many moles of O2 are needed to react with 8.9 moles of Fe? 8.9 mol Fe 3 mol O2 4 mol Fe = 6.7 mol O2 2 H 2 O è 2 H2 + O 2 7. How many moles of O2 are produced when 1.26 moles of H2O is reacted? 1.26 mol H2O 1 mol O2 2 mol H2O = .630 mol O2 8. How many moles of H2O are needed to produce 55.7 moles of H2? 55.7 mol H2 2 mol H2O 2 mol H2 = 55.7 mol H2O 9. If enough H2O is reacted to produce 3.40 moles of H2, then how may moles of O2 must have been made? (a bit challenging, but just think about it and you can probably figure it out) 3.40 mol H2 1 mol O2 2 mol H2 = 1.70 mol O2 2 KClO3 è 2 KCl + 3 O2 10. How many grams of O2 will be formed from 3.76 grams of KClO3? 3.76g KClO3 1 mol KClO3 122.55 g KClO3 3 mol O2 2 l KClO3 32.00 g O2 1 = 1.47 g O2 mol O2 11. How many grams of KClO3 are needed to make 30.0 grams of KCl? 30.0 g KCl 2 mol KClO3 122.55 g KClO3 = 49.3 2 1 ol KClO3 KCl 1 mol KCl 74.55 g KCl KClO3 12. How many grams of KCl will be formed from 2.73 g of KClO3? 2.73 g KClO3 1 mol KCl O3 122.55 g KClO3 74.55 g KCl 2 mol KCl = 1.66 ol KCl 1 2 KCl O3 KCl 4 Fe + 3 O2 è 2 Fe2O3 13. How many grams of Fe2O3 are produced when 42.7 grams of Fe is reacted? 42.7 g Fe 1 mole Fe 55.85 g Fe 2 mol Fe2O3 4 l Fe 159.70 g Fe2O3 1 = 61.0 Fe2O3 = 56.6 Fe2O3 Fe2O3 14. How many grams of Fe2O3 are produced when 17.0 grams of O2 is reacted? 17.0 g O2 1 mol O2 32.00 g O2 2 mol Fe2O3 3 mol O2 159.70 g Fe2O3 Fe2O3 1 15. How many grams of O2 are needed to react with 125 grams of Fe? 125 g Fe 1 mol Fe 55.85 g Fe 3 4 mol O2 mol Fe 32.00 g O2 1 O2 = 53.7 g O2 Some cars can use butane (C4H10) as fuel: 2 C4H10 + 13 O2 è 8 CO2 + 10 H2O 16. How many grams of CO2 are produced from the combustion of 100. grams of butane? 100. g C4H10 1 mol C4H10 8 mol CO2 44.01 g CO2 58.14 g C4H10 2 mol C4H10 1 mol CO2 = 303 g CO2 17. How many grams of O2 are needed to react with of 100. grams of butane? 100. g C4H10 1 mol C4H10 58.14 g C4H10 13 mol O2 2 mol C4H10 32.00 g O2 1 mol O2 358 g O2 18 How many grams of H2O are produced when 5.38g of O2 is reacted? 5.38g O2 1 mol O2 10 mol H2O 32.00 g O2 13 mol O2 18.02 g H2O mol H2O 2.33 g H2O