1. Stoichiometry II

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

3. 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. 1. Make sure the equation is balanced

4. What mass of NaCl is formed from the reaction with 3.20 moles of chlorine gas? Na (s) + Cl 2(g) NaCl (s) 3.20 moles 22 ? g = 374 g NaCl 1 mol NaCl 58.5 g3.20 mol Cl 2 1 mol Cl 2 2 mol NaCl

5. Calculate the moles of hydrogen needed to make 15.0 g of ammonia? NH 3 = 17.0 g/mol N 2 (g) + H 2 (g) NH 3 (g) 15.0 g 32 ? mol 2 mol NH 3 3 mol H 2 15.0 g NH 3 17.0 g NH 3 1 mol NH 3 = 1.32 mol H 2

6. What mass of carbon dioxide is produced from burning 50.0 g of ethane, C 2 H 6 ? 2 C 2 H 6 (g) + 7 O 2 (g) 4 CO 2 (g) + 6 H 2 O (g) = 147 g CO 2 4 mole CO 2 2 mole C 2 H 6 1 mole C 2 H 6 30.0 g C 2 H 6 50.0 g C 2 H 6 44.0 g CO 2 1 mole CO 2 50.0 g ? g mol

7. 4 mole FeS 2 mole Fe 2 O 3 1 mole Fe 2 O 3 159.6 g Fe 2 O 3 36.3 g Fe 2 O 3 87.9 g FeS 1 mole FeS = 40.0 g FeS Fe 2 O 3 = 159.6 g/mol How many grams of FeS are needed to make 36.3 g of Fe 2 O 3 ? FeS (s) + O 2 (g) Fe 2 O 3 (s) + SO 2 (g) FeS = 87.9 g/mol 74 4 2 36.3 g ? g mol

8. What volume of O 2 is needed to make 19.8 L SO 3 ? 2 SO 2 (g) + O 2 (g) 2 SO 3 (g) = 9.90 L O 2 1 mole O 2 2 mole SO 3 1 mole SO 3 22.4 L SO 3 19.8 L SO 3 22.4 L O 2 1 mole O 2 19.8 L ? L mol

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

10. What volume of O 2, in Litres, is needed to completely react with 25.0 g of FeS, at STP? 4 FeS (s) + 7 O 2 (g) 2 Fe 2 O 3 (s) + 4 SO 2 (g) = 11.1 L O 2 7 mole O 2 4 mole FeS 1 mole FeS 87.9 g FeS 25.0 g FeS 22.4 L O 2 1 mole O 2 FeS = 87.9 g/mol 25.0g ? L mol

11. Heat of Reaction

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

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

14. What mass of water is produced in the reaction when 8000 kJ of energy is released? 4 NH 3 + 3 O 2 2 N 2 + 6 H 2 O + 300 kJ 1 mole H 2 O 18.0 g H 2 O 300 kJ 6 mole H 2 O 8000 kJ = 3000 g H 2 O ? g

15.  Heat of reaction is the amount of energy released or absorbed during a chemical reaction.  Heat of reaction can be determined by stoich. 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. 1. Make sure the equation is balanced

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