(use SF, units; show all work; answers in box) 1: Consider the reaction: 2 AgI (s) + Br2(l)  2 AgBr (s) + I2 (g) Ho = -12.0 kJ/mol What is the value of Ho if the reaction is a: tripled? b: reversed and doubled? c: producing solid iodine instead of gaseous? 2. A piece of plastic with a mass of 3.15 kg has a specific heat of 1.14 J/g oC. What is the heat capacity of the piece of plastic? How much heat will it take to raise the temperature of the piece of plastic from 21.7 oC to 126.2 oC? 3: Removing 327 J of heat drops the temperature of a block of copper from 225.3 oC to 218.3 oC. What is the mass of copper? (specific heats are p193 of Chang 7th Ed.) 4: 256 g of aluminum at 212.5 oC are placed in an insulated container with 22.2 g of mercury at 13.8 oC. What is the final temperature for the two metals in the container? 5: Write the equation for calculating the standard enthalpy change of a reaction. Briefly define the variables. 6: Without looking up the values, determine which of the following substances have standard enthalpy of formation (Hof) values that are equal to zero. Br2 (l), CO2 (g), F (g), Hg(s), Li (s), Mn4+ (aq), O3 (g) 7: Predict the value of Hof (greater than, less than or equal to zero) for these elements: a. H2 (l) b. Pb (l) 8: Write the formation reactions for each of the following substances. Include states! a: NaCl (l) b: XeF4 (s) c: H2CO3 (aq) d: Hg2Br2 (s) 9: Calculate the standard heats of reaction for the following reactions. You may look up the standard heats of formation (in Chang 7th Ed. they are p. A-2 to A-6). a. 2 FeCl3 (s) + 3 BaO (s)  Fe2O3 (s) + 3 BaCl2 (s) (If using Chang, treat FeCl3 as having a dot at the end of its heat of formation.) b. 2 HCl (g) + Cu2O (s)  H2O (l) + 2 CuCl (s) 10: a: The reaction of an aqueous monoprotic strong acid (such as HBr (aq)) with an aqueous alkali strong base (such as LiOH (aq)) always has the same heat of reaction regardless of which strong acids and strong base were used. Find the heat of the following reaction using the heats of formation in your textbook. Hint: These are strong electrolytes! a: HBr (aq) + LiOH (aq)  LiBr (aq) + H2O (l) b: Find the heat of the following reaction. (Some strong electrolytes are also involved.) a: MgCl2 (aq) + 2 KOH (aq)  2 KCl (aq) + Mg(OH)2 (s) 11: How many kJ of heat are given off if you burn 195.2 g of butane gas using the following reaction? 2C4H10 (g) + 13 O2 (g)  8 CO2 (g) + 10 H2O(g) Horxn = -5316.6 kJ 12: How many grams of S8 would you need for this reaction to absorb 925.0 kJ of heat? 3 S8 (s) + 16 H2O (g)  8 SO2 (g) + 16 H2S (g) Horxn = 1175.2 kJ 13: From the following data C(graphite) + O2(g)  CO2 (g) H2 (g) + 1/2O2 (g)  H2O(l) 2C2H6(g) + 7O2(g)  4CO2 (g) + 6H2O(l) Calculate the enthalpy change for the reaction: Horxn = -393.5 kJ Horxn = -285.8 kJ Horxn = -3119.6 kJ 2C(graphite) + 3H2 (g)  C2H6(g) 14: Calculate the standard enthalpy change for the reaction 2 Al(s) + Fe2O3(s)  2 Fe(s) + Al2O3 (s) Given that 2Al (s) + 3/2 O2 (g)  Al2O3 (s) 2Fe (s) +3/2 O2 (g)  Fe2O3 (s) Horxn = -1669.8 kJ/mol Horxn = -822.2 kJ/mol 15: You are given the following data: H2 (g)  2H (g) Br2 (g)  2Br (g) H2 (g) + Br2 (g)  2HBr (g) CalculateHo for the reaction: Ho = 436.4 kJ/mol Ho = 192.5 kJ/mol Ho = -72.4 kJ/mol H(g) + Br(g)  HBr(g) 16: 2 K (s) + Fe2O3 (s)  2 FeO (s) + K2O (s) The above reaction is done using 64.46 g of potassium in a calorimeter containing 512 g of water, which goes from 23.0 oC to 55.7 oC. Find Hrxn under these conditions. (This one has a very tricky last step! Most of you will be off by a factor of 2.) Be careful with units and convert them to be consistent as needed! 17- How much heat does it take to heat 10.0 g of H2O (s) at -50.0 °C to H2O (g) at 140.0 °C? Given: cs (ice) = 2.09 J/g °C cs (steam) = 0.4584 cal/g °C H°fus (ice) = 6.01 kJ/mol H°vap (water) = 40.7 kJ/mole 18- If you dump an 187 g iron sword at 872 °C into a water barrel containing 3.186 kg of water at 19.8 °C, what is the final temperature? (Assume no steam.) 19- 10.0 g of ethene (C2H4 (g)) were burned in excess oxygen in a calorimeter containing 163 g of water. The calorimetry constant (heat capacity of the calorimeter) was C = 21.7 kJ/°C. What was the temperature rise of the calorimeter? 
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