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Stoichiometry II

Stoichiometry II. Solve stoichiometric problems involving moles, mass, and volume, given a balanced chemical reaction . Include : heat of reaction Additional KEY Terms. 1. Make sure the equation is balanced. 2. start with what you know 3. convert to moles

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Stoichiometry II

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  1. Stoichiometry II

  2. Solvestoichiometricproblems involving moles, mass, and volume, given a balanced chemical reaction. • Include: heat of reaction • Additional KEY Terms

  3. 1. Make sure the equation is balanced 2. start with what you know 3. convert to moles 4. "transition step"(using molar ratios) 5. convert to desired units This is the only place where you use the coefficients.

  4. Na(s) + Cl2(g) NaCl(s) What mass of NaCl is formed from the reaction with 3.20 moles of chlorine gas? 2 2 ? g 3.20 moles 3.20 mol Cl2 2 mol NaCl 58.5 g 1 mol NaCl 1 mol Cl2 = 374 g NaCl

  5. N2 (g) + H2 (g) NH3 (g) Calculate the moles of hydrogen needed to make 15.0 g of ammonia? 3 2 ? mol 15.0 g NH3 = 17.0 g/mol 15.0 g NH3 1 mol NH3 3 mol H2 2 mol NH3 17.0 g NH3 = 1.32 mol H2

  6. What mass of carbon dioxide is produced from burning 50.0 g of ethane, C2H6? 2 C2H6 (g) + 7 O2 (g) 4 CO2 (g) + 6 H2O (g) 50.0 g ? g mol mol 50.0 g C2H6 1 mole C2H6 4 mole CO2 44.0 g CO2 2 mole C2H6 30.0 g C2H6 1 mole CO2 = 147 g CO2

  7. FeS(s) + O2 (g) Fe2O3 (s) + SO2 (g) How many grams of FeS are needed to make 36.3 g of Fe2O3? 4 4 7 2 ? g 36.3 g mol mol FeS = 87.9 g/mol Fe2O3 = 159.6 g/mol 36.3 g Fe2O3 1 mole Fe2O3 4 mole FeS 87.9 g FeS 159.6 g Fe2O3 2 mole Fe2O3 1 mole FeS = 40.0 g FeS

  8. 2 SO2 (g) + O2(g)2 SO3 (g) What volume of O2 is needed to make 19.8 L SO3? ? L 19.8 L mol mol 19.8 L SO3 1 mole SO3 1 mole O2 22.4 L O2 22.4 L SO3 2 mole SO3 1 mole O2 = 9.90 L O2

  9. What volume of chlorine gas is needed to react with 10.0 g of sodium? Na (s) + Cl2(g) NaCl (s) 2 2 10.0 g ? L mol mol 10.0 g Na 1 mole Na 1 mole Cl2 22.4 L Cl2 22.99 g Na 2 mole Na 1 mole Cl2 = 4.87 L Cl2

  10. 4 FeS (s) + 7 O2 (g) 2 Fe2O3 (s) + 4 SO2 (g) What volume of O2, in Litres, is needed to completely react with 25.0 g of FeS, at STP? 25.0g ? L mol mol FeS = 87.9 g/mol 25.0 g FeS 1 mole FeS 7 mole O2 22.4 L O2 87.9 g FeS 4 mole FeS 1 mole O2 = 11.1 L O2

  11. Heat of Reaction Heat of Reaction

  12. A + energy B A B + energy The energy change that accompany a chemical reaction are called heat of reaction. Endothermic reactions - the absorption of energy is included as a reactant. Exothermic reactions - the release of energy is included as a product.

  13. Find the heat released or absorbed by stoichiometry. What heat is produced from burning 60.0 g of ethane (C2H6), if the heat of combustion is 1560 kJ/mol of ethane? 2 C2H6(g) + 7 O2(g) 4 CO2(g) + 6 H2O(g) 60.0 g C2H6 1 mole C2H6 1560 kJ 1 mole 30.0 g C2H6 = 3120 kJ

  14. 4 NH3 + 3 O2 2 N2 + 6 H2O + 300 kJ What mass of water is produced in the reaction when 8000 kJ of energy is released? ? g 6 mole H2O 18.0 g H2O 8000 kJ 1 mole H2O 300 kJ = 3000 g H2O

  15. 1. Make sure the equation is balanced 2. start with what you know 3. convert to moles 4. "transition step"(using molar ratios) 5. convert to desired units This is the only place where you use the coefficients. • Heat of reaction is the amount of energy released or absorbedduring a chemical reaction. • Heat of reaction can be determined by stoich.

  16. CAN YOU / HAVE YOU? • Solvestoichiometricproblems involving moles, mass, and volume, given a balanced chemical reaction. • Include: heat of reaction • Additional KEY Terms

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