Ideal gas except for the specification of these constants. The results of the quantum Boltzmann gas are used in a number of cases including the Sackur–Tetrode equation for the entropy of an ideal gas and the Saha ionization equation for a weakly ionized plasma. The classical thermodynamic properties of an ideal gas can be described by two equations of state: The ideal gas law is the equation of state for an ideal gas, given by: where The ideal gas law is an extension of experimentally discovered gas laws. It can also be derived from microscopic considerations. Real fluids at low density and
Negative number sum of a number and its negation is equal to zero: That is, the negation of a positive number is the additive inverse of the number. Using algebra, we may write this principle as an algebraic identity: This identity holds for any positive number . It can be made to hold for all real numbers by extending the definition of negation to include zero and negative numbers. Specifically: For example, the negation of is . In general, The absolute value of a number is the non-negative number with the same magnitude. For example, the absolute value of and the absolute