An athlete can apply an instant cold pack after an injury to help reduce swelling. An instant cold pack is a small bag containing two pouches, one filled with water and the other filled with ammonium nitrate (NH4NO3). The athlete activates the pack by squeezing the bag to break the pouches open, allowing the water and ammonium nitrate to mix. When this happens, the ammonium nitrate dissolves in the water, forming ammonium ions (NH4+) and nitrate ions (NO3−), and the pack becomes cold. Is this chemical exothermic or endothermic?

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

what is the average time it took the car to travel 0.25 meters?

⇒ 2.23 seconds

what is the average time it took the car to travel 0.50 meters?

⇒ 3.13 seconds

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.