Instant cold packs used to treat athletic injuries contain solid NH, NO3 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 NH, NO3(s) + H₂O(1)→ NH4NO3(aq) AH = +257 kJ V Part A What is the final temperature in a squeezed cold pack that contains 42 5 g of NH, NO, dissolved in 125 mL of water? Assume a specific heat of 4.18J/(g° C) for the solution, an initial temperature of 30 0 °C, and no heat transfer between the cold pack and the environment. ΕΠΙ ΑΣΦ • A C E ? °C Request Answer Submit

Instant cold packs used to treat athletic injuries contain solid NH, NO3 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 NH, NO3(s) + H₂O(1)→ NH4NO3(aq) AH = +257 kJ V Part A What is the final temperature in a squeezed cold pack that contains 42 5 g of NH, NO, dissolved in 125 mL of water? Assume a specific heat of 4.18J/(g° C) for the solution, an initial temperature of 30 0 °C, and no heat transfer between the cold pack and the environment. ΕΠΙ ΑΣΦ • A C E ? °C Request Answer Submit

Chemistry & Chemical Reactivity

10th Edition

ISBN:9781337399074

Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Publisher:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Chapter18: Principles Of Chemical Reactivity: Entropy And Free Energy

Section: Chapter Questions

Problem 102SCQ

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9.83 A student performing a calorimetry experiment combined 100.0 mL of 0.50 M HCl and 100.0 mL of 0.50 M NaOH in a coffee 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. Will the T observed he 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 HCl and 100.0 mL of 1.00 M NaOH. Will the T observed he greater than, less than, or equal to that in the first experiment, and why?
9.96 Most first aid "cold packs" are based on the endothermic dissolution of ammonium nitrate in water: NH4NO3(s)NH4+(aq)+NO3(aq) H= 25.69 kJ A particular cold pack contains 50.0 g of NH4NO3 and 125.0 g of water. When the pack is squeezed, the NH4NO3dissolves in the water. If the pack and its contents are initially at 24.0°C, what is the lowest temperature that this bag could reach? (Assume that the ammonium nitrate solution has a specific heat of 4.25J g-l K-l, and that the heat capacity of the bag itself is small enough to be neglected.)
Are any of the following exothermic processes not spontaneous under any circumstances? (a) Snow forms from Liquid water. (b) Liquid water condenses from water vapor. (c) Fossil fuels burn to form carbon dioxide and water. (d) Monomers react to form a polymer.
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A wad of steel wool (specific heat=0.45J/gC) at 25C is misplaced in a microwave oven, which later is accidentally turned on high. The oven generates microwaves of 13.5 cm wavelength at the rate of 925 moles of those photons per second. All of the photons are converted to high-heat energy, raising the temperature of the steel wool. Steel wool reacts explosively with the oxygen in the oven when the steel wool reaches 400.0C. If the steel wool explodes after 1.55 seconds, how many grams of steel wool were accidentally put into the oven?
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