Follow the approach in Section 5.7 to derive the equation for the dependence of concentration on spatial position in a tubular reactor of length L operating at steady state, in which the radius is R and the volumetric flow rate is q. Assume that there is a single reaction. As in the membrane example, you may assume that there is no mixing in the axial direction, but that the concentration is uniform over any cross-section orthogonal to the direction of flow. How does this equation relate to the equation for the batch reactor?