EXAM PRACTIVE QUESTIONS Chapter 15 1 The roasting of 48 7 g of ZnS at constant pressure liberates 220 kJ of heat Calculate the cid 39 H for this reaction 2 ZnS s 3 O2 g cid 111 2 ZnO s 2 S O2 g 440 kJ mol rxn 2 From the following data at 25 cid 113 C H2 g Cl2 g cid 111 2 HCl g 2 H2 g O2 g cid 111 2 H2O g cid 39 H cid 113 483 7 kJ cid 39 H cid 113 185 kJ Calculate cid 39 H cid 113 at 25 cid 113 C for the reaction below 4 HCl g O2 g cid 111 2 Cl2 g 2 H2O g 114 kJ 3 Given the enthalpy changes for the following reactions calculate cid 39 Hf cid 113 for CO g Hint if CO is formed it must be a product in the final reaction which is not given you must write it C graphite O2 g cid 111 2 CO2 g cid 39 H cid 113 393 5 kJ CO g O2 g cid 111 CO2 g cid 39 H cid 113 283 0 kJ C graphite O2 g cid 111 CO g cid 39 H cid 113 110 5 kJ 4 Calculate cid 39 H cid 113 at 25 cid 113 C for the reaction below Fe3O4 s CO g cid 111 3 FeO s CO2 g cid 39 Hf cid 113 kJ mol 1118 110 5 272 393 5 19 kJ 5 How much heat is released or absorbed in the reaction of 10 0 g of SiO2 quartz SiO2 s 4 HF aq cid 111 SiF4 g 2 H2O cid 34 cid 39 Hf cid 113 kJ mol 910 9 320 8 1615 285 8 1 2 kJ 6 How much work is done when the following reaction occurs at constant pressure N2 g O2 g cid 111 2 NO g 0 work cid 3 cid 3 cid 3 7 Calculate the average bond energy in kJ per mol of bonds for the C H bond from the following data 415 9 kJ C graphite 2 H2 g cid 111 CH4 g cid 39 Hrxn cid 113 74 81 kJ cid 39 Hf cid 113 for H g 218 0 kJ cid 39 Hf cid 113 for C g 716 7 kJ 8 A system performs 390 L cid 152 atm of pressure volume work L cid 152 atm 101 325 J on its surroundings and it releases 9800 kJ of heat to its surroundings What is the change in the internal energy 9840 kJ 9 Assuming the gases are ideal calculate the amount of work done in J for the conversion of 1 00 mole of CO g at 75 cid 113 C in the reaction below The value of R is 8 314 J mol cid 152 K Ni s 4CO g cid 111 4 Ni CO 4 g cid 3 cid 3 cid 3 cid 3 cid 3 cid 3 cid 3 cid 3 cid 3 8680 J cid 3 10 Evaluate cid 39 S cid 113 for the reaction below at 25 cid 113 C and 1 atm 3 NO2 g H2O cid 34 cid 111 2 HNO3 aq NO g S cid 113 J mol cid 152 K 240 69 91 146 210 7 287 2 J K 11 Calculate cid 39 G cid 113 at 298 K for the reaction below N2O4 g 2 N2H4 cid 34 cid 111 3 N2 g 4 H2O g cid 39 Gf cid 113 KJ mol 97 82 149 9 0 228 6 1311 kJ mol 12 Evaluate cid 39 G cid 113 at 25 cid 113 C for the reaction below P4O10 s 6 H2O cid 34 cid 111 4 H3PO4 s cid 39 Hf cid 113 KJ mol 2984 285 8 1281 S cid 113 J mol cid 152 K 228 9 69 91 110 5 363 7 kJ