LR 11 03 2014 1 When 0 721 g of titanium is burned in a bomb calorimeter according to the equation Ti s O2 g TiO2 s the temperature of the calorimeter and its contents increases from 25 0 to 53 8 C If the heat capacity of the calorimeter is 9 84 kJ C what is the enthalpy change in kJ mol for 1 mole of tin q C T 9 84kJ C 28 8 C 283 kJ x 47 9 g Ti 1 88 x 104 kJ mol 0 721g 1 mol Ti 2 Given the reaction 2 NO g O2 g What is H for NO2 g 2 NO2 g H 114kJ NO g O2 g H 114kJ 28 5 kJ 4 3 Using Hess s law calculate the value of H for the reaction 2 NF3 g Cu s N2F4 g CuF2 s using the following equations a b c 2 NF3 g 2 NO g N2F4 g 2 ONF g NO g F2 g ONF g Cu s F2 g CuF2 s H 82 9 kJ H 157 kJ H 531 kJ 2 NF3 g 2 NO g N2F4 g 2 ONF g Cu s F2 g CuF2 s 2 ONF g 2NO g F2 g H 82 9 kJ H 531 kJ H 2 157kJ 2 NF3 g Cu s N2F4 g CuF2 s 300kJ 1 4 Calculate the value of H for the reaction 3 Fe s 4 H2O g Fe3O4 s 4 H2 g using the equations below a b c FeO s H2 g Fe s H2O g 3 FeO s O2 g Fe3O4 s H2 g O2 g H2O g 3Fe s 3H2O g 3FeO s 3H2 g 3 FeO s O2 g Fe3O4 s H2O g H2 g O2 g H H H 3Fe s 4H2O g Fe3O4 s 4H2 g 5 25 0 kJ 318 kJ 242 kJ 3 25 0kJ 318kJ 242 kJ 149kJ Which of the following reactions represent s standard enthalpy of formation N2 g 2 H2 g N2H4 g 2 H2 g O2 g 2 H2O N2 g 3 2 H2 g NH3 2Fe s 3 2O2 g Fe2O3 s 6 Calculate the standard enthalpy change for the decomposition of calcium carbonate given the standard enthalpies of formation CaCO3 s 1207 CaO s 636 and CO2 g 394 kJ mol CaCO3 s CaO s CO2 g H 1mol 636kJ mol 1mol 394 kJ mol 1mol 1207kJ mol 7 177kJ Estimate the enthalpy change for the reaction given the following bond enthalpies in kJ mol N H 391 N N 941 N N 163 H H 436 and compare this to the enthalpy change using standard enthalpies of formation N2H4 g N2 g 2 H2 g H N N H N N H H Bonds broken 4mol N H 4 391kJ 1564kJ 1mol N N 163kJ 1721 kJ 2H H Bonds formed 1 mol N N 941kJ 2 mol H H 2 436kJ 1813kJ 2 H 1721kJ 1813kJ 92 kJ 3
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