Many systems involve gas mixtures. Understanding ideal gas behavior and mixtures including air and water vapor are prerequisites to considering air conditioning and combustion processes. Using Dalton's model to relate pressure, volume, and temperature to calculate changes in enthalpy and entropy of ideal gas mixtures benefits thermodynamic analysis. Understanding key terms such as humidity ratio and dew point temperature play a vital role for practicing cycles involving water vapor. These micro-thermodynamic problems are significant in identifying problems and improving thermodynamic systems in real world applications.