Physical changes that involve liquids and aqueous solutions can be studied using a polystyrene calorimeter like the one shown in Figure 1. Such materials can be applied to practical thermochemical systems. For example, when athletes are injured, they may immediately hold an ‘instant cold pack’ against the injury; and over time, the athlete may apply ‘instant hot pack’ to help recover. The medical hot/cold pack operates on the principle that certain salts dissolve endothermically in water, while others dissolve exothermically. The amount of heat per unit mass involved in the dissolving of a compound is a characteristic property of that substance. It is called the enthalpy of solution. The purpose of this experiment is to use calorimetry to determine the enthalpy of solution of an unknown salt, and then to use that value to identify the salt in a medical hot/cold pack, from a list of possible candidates.
Categories: Lab/Student Activity
The students will be creating a flying device, choosing sponsors from industries that use aviation technology, and entering the flying race. In order to prepare the students for this inquiry, the... read more
This resource shows the reader how to use the Clips App in a way that allows students to create a digital story about a cell. There are excellent examples of how the final product is supposed to look... read more