Heat Capacity and Calorimetry

Overview of Heat Capacity

The heat capacity of a substance is the amount of heat energy required to raise its temperature by one degree Celsius.
It’s typically measured in Joules per degree Celsius (J/°C) or Joules per Kelvin (J/K).
Heat capacity is an intensive property, meaning it is dependent on the amount of the substance in question.
The specific heat capacity, or simply specific heat, is the heat capacity per unit mass. It is an individual property of the substance.
Water has a notably high specific heat, which makes it effective at moderating temperature fluctuations (for example, in bodies of water on the Earth’s surface).

Calorimetry is a technique used to measure changes in thermal energy or heat of chemical reactions or physical changes.
The equipment used in this method is called a calorimeter.
A coffee-cup calorimeter is a common example of a simple calorimeter, which is essentially an insulated container filled with water.
In a calorimetry experiment, a reaction is initiated in a controlled, insulated environment. The temperature change of the known volume of water is measured.
This data is used to extrapolate the enthalpy change of the reaction.

The heat (q) gained or lost in a chemical reaction can be calculated via q = mc∆T, where:
- m is the mass of the substance (in g)
- c is the specific heat capacity of the substance (in J/g°C)
- ∆T is the change in temperature (in °C)
If the calculated heat (q) value is positive, the reaction is endothermic. If it’s negative, the reaction is exothermic.
This formula can be used to find the missing variable when the others are known.

Understanding heat capacity is essential for predicting how a substance will respond to added heat.
This theme is important in many real-world contexts, including climate science (e.g., how the ocean buffers global temperature shifts) and engineering (e.g., designing materials to withstand specific amounts of heat).
Calorimetry allows scientists to determine the heats of reaction or formation, heats of solution, and to measure energy changes in physical and chemical processes.
This is vital in many areas of science and technology, such as creating efficient energy sources, studying metabolic processes in biology, and developing materials for specific heat tolerances in engineering.