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
Myself and two other teachers came together to team teach strands of Grade 9 Geography, Science, and English that could be looked at through a farming lens. Our class had already partnered with a... read more
This activity is a good opportunity for students to exercise their hypothesis-generating skills, practice making quantitative observations, and apply what they have learned about the fire triangle... read more
Cells require a constant supply of glucose and oxygen to produce energy. Cellular respiration occurs in the mitochondria of a cell. As a result of this process, large quantities of waste carbon... read more