# Glossary of Thermodynamic Terms

beginning with the letter...

G
 Primary Word Secondary Word Definition Tutorial Page Link
 gas A phase in which molecules are far from each other (a dispersed phase) and the molecules move randomly.  Molecules in a gas phase have more translational, vibrational, and rotational energies than liquids or solids at the same temperature and thus have a higher internal energy. 2A4 gas diatomic A gas in which every molecule consists of only two identical atoms.  For example: hydrogen, oxygen, nitrogen. 2A4 gas ideal A gas that obeys the ideal-gas equation of state. All real gases approach ideality at low pressures and high temperatures.  For most gases, less than 1% error is incurred by treating them as ideal gases as long as the molar volume is greater than 20 L/mole.  Diatomic gases and most noble gases can be treated as ideal gases as long as their molar volume exceeds 5 L/mole 2D2, 2E2, gas mixtures gas monatomic A gas in which all of the molecules consist of only one atom.  Noble gases like He and Ar are examples of monatomic gases. 2A4 gas noble Gases in the right-most column of the periodic table :  He, Ne, Ar, Kr Xe Rn. 2A4 gas real In principle, all gases are real gases.  In practice, gases that deviate from the Ideal Gas EOS by more than 1% are considered to be non-ideal or real gases. 2E3 gas power cycle 4F3 gas turbine 9E2 gauge (gage) pressure Also known as Gage Pressure.  The difference between the absolute pressure and atmospheric pressure.  Gauge pressure is what is normally read from a pressure gauge.  You must ADD atmospheric pressure to the gauge pressure to obtain the absolute pressure.  Gauge pressures CAN be negative !  [ atm, kPa, bar, psig, etc. ] 1D3 gc 1A5, 1B5, generalized compressibility chart 2E1  ,  10  ,  11 Gibbs equation First 7D1  ,  4 - 5  ,  6  ,  8, 7E1  ,  2  ,  5, Gibbs equation Second 7D1  ,  5  ,  8, 7E1  ,  2  ,  6, Gibbs phase rule Degrees of Freedom, F = 2 + m - pi, where m is the number of chemical species in the system and pi is the number of phases in the system. 3C4, 3D1, gravitational acceleration 1A5 gravitational work 4A20  ,  24