9.1 Introduction to Entropy

Entropy

Entropy is defined as the number of microstates that a system can have. Entropy is represented with the variable ${S}$ and has units of joules per mole degree kelvin. A microstate is essentially a configuration that a system can be in. Entropy is related to the amount of microstates in a system through the equation below. Note that you will not need to know this equation for the AP Exam but it is important to understand how entropy is fundamentally defined: ${S=k_Bln(W)}$, where ${S}$ is the entropy of a system, ${k_B}$ is the Boltzmann constant, equal to ${1.38*10^{-23} \frac{J}{K}}$, and ${W}$ is the number of microstates in the system