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8.52 When a solution containing 8.00 g of NaOH in 50.0 g of water at 25.0 °C is added to a solution of 8.00 g of HCI in 250.0 g of water at 25.0 °C in a calorimeter, the temperature of the solution increases to 33.5 °C. Assuming that the specific heat of the solution is 4.18 J/(g. C) and that the calorimeter absorbs a negligible amount of heat, calculate AH in kilojoules for the reaction NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(1) When the experiment is repeated using a solution of 10.00 g of HCI in 248.0 g of water, the same temperature increase is observed. Explain. 8.53 Instant cold packs used to treat athletic injuries contain solid NH4NO3 and a pouch of water. When the pack is squeezed, the pouch breaks and the solid dissolves, lowering the temperature because of the endothermic reaction NH4NO3(s)→→ NH4NO3(aq) AH = +25.7 kJ What is the final temperature in a squeezed cold pack that contains 50.0 g of NH4NO3 dissolved in 125 mL of water? Assume a specific heat of 4.18 J/(g. C) for the solution, an initial temperature of 25.0 °C, and no heat transfer between the cold pack and the environment. H₂O
8.103 Tell whether reactions with the following values of AH and AS are spontaneous or nonspontaneous and whether they are exothermic or endothermic: a. AH -128 kJ; AS = +35 J/K at 500 K -140 J/K at 250 K +95 J/K at 800 K b. AH = +67 kJ; AS = c. AH = +75 kJ; AS =