A reactive flow, the gelation of sodium acrylate (SA), was carried out in a cuboidal cavity with the top surface undergoing sinusoidal periodic motion. The instantaneous two-dimensional planar velocity fields during gelation were obtained using particle image velocimetry. The experiments were carried out with different plate velocities and different amounts of accelerator (TEMED). The temporal and spatial variations of the velocity components were analyzed. The magnitude of the velocity components was found to decrease with the progress of reaction due to gel formation. The role of mixing on the reaction is understood from the amount of gel formed at different plate velocities. Gel formation patterns are explained in terms of the mixing characteristics of the periodic flow. The periodic variation of point velocities showed the presence of higher harmonics in the flow.