Self cooling ice packs are often used at football games to put on injuries to stop swelling. the pack contains a small bag of water surrounded by a larger bag containing a chemical. when the pack is punched the chemical and the water mix and the pack becomes very cold. identify the type of change taking place.justify your answers
Answers
Look up ice pack in Wiktionary, the free dictionary.
An ice pack
An ice pack with gel leaking out of a hole in the upper left corner
Shipment of vaccine in insulated box with gel packs
An ice pack or gel pack is a portable plastic bag filled with water, refrigerant gel, or liquid. For use the contents are frozen in a freezer. Both ice and other non-toxic refrigerants (mostly water) can absorb a considerable amount of heat before they warm above 0 °C, due to the high latent heat of fusion of water. These packs are commonly used to keep food cool in portable coolers, or as a cold compress to alleviate the pain of minor injuries, or in insulated shipping containers to keep products cool during transport.[1]
Ice packs are used in coolers to keep perishable foods (especially meats, dairy products, eggs, etc.) below the 5–75 °C (41–167 °F) danger zone when outside a refrigerator or freezer, and to keep drinks pleasantly cool. The amount of ice needed varies with the amount of food, its initial temperature, the thermal insulation of the cooler, and the ambient temperature and exposure to direct sunlight. Ice initially well below freezing temperature will last a little longer.
Water has a much higher latent heat of fusion than most substances, and a melting temperature which is convenient and easily attained with, for example, a household freezer. Additives to improve the properties of water are often used. For example, substances can be added to prevent bacterial growth in the pack, or to prevent the water from solidifying so it remains a thick gel throughout use.
Gel packs are often made of non-toxic materials that will remain a slow-flowing gel, and therefore will not spill easily or cause contamination if the container breaks. Gel packs may be made by adding hydroxyethyl cellulose (Cellusize),[2][3] sodium polyacrylate[4], or vinyl-coated silica gel.
Endothermic chemical reactions happen in the self-cooling ice pack.
• In these sale cooling ice packs , there are two chambers.
The chambers contain :
A) Water
B) Ammonium nitrate
• When we puncture these packs the Ammonium Nitrate and water gets mixed with each other.
• After that an endothermic chemical reaction takes place inside the pouch which absorbs the surroundings heat energy.
• That's why when we apply that pack on the injured portion the pack gives a cold feeling because it is absorbing the heat.