Free Essays, Term Papers, Research Papers at Anti Essays

Experiment 8
Dystan Medical Supply Company—Cold Packs and Hot Packs


IN CHEM S125 1705 EXP CHEMISTRY I HONORS




















Introduction

Hot and cold packs are used to treat injuries in the hospital to minor injuries at home. For example, cold packs are used to keep a patient’s body temperature down when they become deathly hot or to decrease inflammation in a sprained ankle. Hot packs can be used to reduce muscle spasms, muscle soreness, inflammation, and relieve pain. Since the demand for hot and cold packs is so great, companies like Dystan Medical Supply produce and sell cold and hot packs in large quantities. These packs are made by dissolving salts in water. When an ionic compound dissociates in water it either absorbs energy from the water or releases energy to the water. When the compound absorbs energy, it does so through heat energy. This is an endothermic process. An Exothermic process would be one in which energy is released to the surroundings. In this case hot packs are exothermic and cold packs are endothermic. In general a pack is created by using a plastic bag which has a compartment of water and a compartment of salt. The bag is broken and the two mix either absorbing or emitting heat. The amount of heat depends on the salt’s concentration in the water.1

In chemistry, calorimeters are constructed to find the enthalpy of reactants and calculate the heat evolved. At constant pressure the enthalpy is the heat gained or lost by a system. A calorimeter is a device that is a closed system. Therefore, no energy can enter the system, so any change in temperature is due to the substances within the calorimeter. For this experiment, water was the substance that is put into the calorimeter and then a salt was added and the initial...