Abstract: Nonlinear stimulation of the vorticity mode caused by losses in the momentum of sound in a chemically reacting gas, is considered. The instantaneous dynamic equation which describes the nonlinear generation of the vorticity mode, is derived. It includes a quadratic nonlinear acoustic source. Both periodic and aperiodic sound may be considered as the origin of the vorticity flow. In the non-equilibrium regime of a chemical reaction, sound and its nonlinear effects behave unusual. There may exist vortices whose direction of rotation is opposite to that of the vortices in the standard thermoviscous flows. This is illustrated by example relating to periodic sound. The theory and examples consider cases of both equilibrium and non-equilibrium regime of a chemical reaction.