This study takes into account the Soret effect, the heat source/sink, and the chemical reaction on a time-dependent natural convection fluid flow through a vertical and infinite tube. A ramped boundary condition for both temperature and concentration is imposed on the wall of the tube. Analytical solutions of the governing equations are obtained with the aid of the Laplace transform and laid out as relations in modified Bessel functions. These solutions are intricate and arduous to invert; thus, a numerical approach, the Riemann sum approximation method, is utilized. A comprehension of the flow pattern is gained by the use of graphs to lay out the temperature, concentration, and velocity, while tables are used to exhibit the skin-friction, Nusselt, and Sherwood numbers. The time-dependent solutions at large time values are compared to the independent closed-form steady-state solutions, which are shown to be in good agreement. The study uncovered that as the heat source and generative chemical reaction increase, the Nusselt and Sherwood numbers, respectively, decrease until flow reversal sets in.