12) Given the data in the table below, AH°rxn for the reaction below is 4NH3 (g) +502 (g) 4NO (g) + 6H2O (1) Substance AHf° (kJ/mol) kJ. 122 12) H2O (1) -286 H2O (g) -242 NO (g) 90 NO2 (g) 34 HNO3 (aq) -207 NH3 (g) -46 A)-1540 B)-1892 C) -1172 D)-150

A sample of ethanol, C2H5OH, weighing 2.84 g was burned in an excess of oxygen in a bomb calorimeter. The temperature of the calorimeter rose from 25.00C to 33.73C. If the heat capacity of the calorimeter and contents was 9.63 kJ/C, what is the value of q for burning 1.00 mol of ethanol at constant volume and 25.00C? The reaction is C2H5OH(l)+3O2(g)2CO2(g)+3H2O(l) Is q equal to U or H?

When 1.000 g of ethylene glycol, C2H6O2, is burned at 25C and 1.00 atmosphere pressure, H2O(l) and CO2(g) are formed with the evolution of 19.18 kJ of heat. a Calculate the molar enthalpy of formation of ethylene glycol. (It will be necessary to use data from Appendix C.) b Gf of ethylene glycol is 322.5 kJ/mol. What is G for the combustion of 1 mol ethylene glycol? c What is S for the combustion of 1 mol ethylene glycol?

A student performing a calorimetry experiment combined 100.0 ml. of 0.50 M HCI and 100.0 ml. of 0.50 M NaOH in a StyrofoamTM cup calorimeter. Both solutions were initially at 20.0 C, but when the two were mixed, the temperature rose to 23.2 C (a) Suppose the experiment is repeated in the same calorimeter but this time using 200 mL of 0.50 M HCl and 200.0 ml of 0.50 M NaOH. WIII the AT observed be greater than, less than, or equal to that in the first experiment, and why? (b) Suppose that the experiment is repeated once again in the same calorimeter, this time using 100 mL of 1.00 M HCI and 100.0 ml. of 1.00 M NaOH. Will the T observed be greater than, less than, or equal to that in the first experiment, and why?