A few laws about ideal gases including Boyle’s law and Charles law. Also, the second picture is when the gases won’t act ideal.

A few laws about ideal gases including Boyle’s law and Charles law. Also, the second picture is when the gases won’t act ideal.

Thermodynamics

*See previous posts about thermal physics*

Heat capacity *c* is a measure of the amount of thermal energy *Q* can be put into a system before we see a change in
its temperature Δ*T*. It is defined by the equation

where Δ*T* may be defined as Δ*T* = *T* - *T*_{0} for an initial temperature *T*_{0} and a final temperature *T*,
so

Therefore, if you put 5 J of energy into some volume of liquid, we’ll call it *X*, which is at an initial
temperature *T*_{0} = 20°C and observed its temperature change to *T* = 25°C then it would have a heat capacity
*c _{X}*

This is particularly useful for engineering purposes because a heat capacity can be used to characterise gases and
materials *etc*. For example, the specific heat capacity *c* of a material is found using its heat capacity per unit mass:

(note that this equation assumes that the heat capacity is independent of mass – *i.e.* for no phase
transitions).