In this video, students review the concept of thermal energy as the product of mass, specific heat capacity, and the change in temperature. Thermal energy (Q), in Joules, is the measure of the amount of energy required to raise the temperature of a substance a certain number of degrees. Or, conversely, the measure of how much energy is released to the environment, should an object cool down. The calculations remind us that we are always considering the transfer of energy within systems.
Students are also reminded about the nature of exothermic versus endothermic reactions. In the former, energy is released by the chemical reaction, and in the latter, it is absorbed. As such, the notation for energy in exothermic reactions is negative (Joules) and for endothermic reactions is positive.
- To describe qualitatively the relationship between the change in thermal energy (quantity of heat) of a substance, its mass, its specific heat capacity and the variations in temperature to which it is exposed
- To apply the mathematical relationship between thermal energy, mass, specific heat capacity and temperature variation (Q = mcΔT)
- To distinguish an endothermic reaction from an exothermic reaction according to perceptible signs
- To distinguish an endothermic reaction from an exothermic reaction according to the position of the energy term in the chemical equation