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.
Students will be completing the assignment entitled Making Molecules (see hand-out link below) created by science-class.net where they will have to create models of different compounds using beads... read more
Categories: Lab/Student Activity
Students work in groups to complete a hydraulic/pneumatic lab with syringes to examine the forces involved and the strength of fluid power Final project is the "firefighting Robotic Arm" - in... read more