Heat Capacity
Heat capacity is a crucial thermodynamic property that quantifies the amount of heat needed to change the temperature of a substance by one degree Celsius (or one Kelvin). It is essential when measuring heat transfer in various thermodynamic processes.
The equation for heat transfer can be expressed as:
$$ q = C \Delta T $$
where:
- $q$ is the heat supplied,
- $C$ is the heat capacity of the substance,
- $\Delta T$ is the change in temperature.
When we talk about heat capacity, it's important to differentiate between two key forms:
1. Molar Heat Capacity ($C_m$): This is the heat capacity per mole of a substance, defined as the amount of heat needed to raise the temperature of one mole by one degree Celsius.
2. Specific Heat Capacity ($c$): This is defined as the amount of heat needed to raise the temperature of one gram of a substance by one degree Celsius.
Additionally, in thermodynamics, we categorize properties as extensive (dependent on the amount of substance) or intensive (independent of the amount of substance). Heat capacities are classified as extensive properties, while specific heat capacities are intensive.
This distinction is critical for thermodynamic calculations involving phase changes and chemical reactions, where knowing how a substance behaves under heating or cooling is vital for appropriate applications.