The local equilibrium flows of ionized chemically homogeneous monatomic gases are considered. Macroscopic conservation equations for momentum, energy, total number of the ions with maximum charge and total number of electrons (both connected and free) are used. A series of integral relations are deduced for these equations. Analytical formula that allows us to investigate to the influence of electron energy and thermal ionization on sound velocity is obtained. For an illustration the dependencies on temperature are deduced for equilibrium concentration components and adiabatic coefficient in ionized helium with various density.