The bulk or second viscosity is appreciably manifested in the flow of multiphase media and reacting gases and characterizes the energy exchange between translational and internal degrees of freedom of particles of the medium. The bulk-viscosity effect arises in the processes that are accompanied by a fast change in the volume (density) of the medium. The pressure determined only by the translational degrees of freedom proves to be first higher than in the case of an instant energy exchange. The solution of the problem in such a formulation is determined from the coupled consideration of the equations of gas dynamics and the algorithms of the rigorous kinetic theory. The calculations carried out show that taking into account the bulk viscosity in the equations of flow results in a mutually related variation of temperature, concentration of gas-mixture components, the shock-layer thickness, and the shockwave structure, which affects the parameters of the non-equilibrium flow.