The Second Law of Thermodynamics states that heat energy cannot transfer from a body at a lower temperature to a body at a higher temperature without the addition of energy. To assess the spontaneity of a process, we must use a thermodynamic quantity known as entropy (S). Entropy (S) is typically defined as the level of randomness (or disorder) of a system or a measure of energy dispersal of the molecules in the system. Increasing the volume of a substance increases the number of positions where each molecule could be, which increases the number of microstates. Therefore, any change that results in a higher temperature, more molecules, or a larger volume yields an increase in entropy. Here, the number of particles increases, so the entropy also increases.