Pure water at 26.1°C is flowing at a velocity of 0.0305 m/s in a tube having an inside diameter of 6.35 mm. The tube is 1.829 m long, with the last 1.22 m having the walls coated with benzoic acid. Assuming that the velocity profile is fully developed, calculate the average concentration of benzoic acid at the outlet. Use the physical property data from Example 21.3-2. [Hint: First, calculate the Reynolds number Dυrho/μ. Then, calculate NReNSc (D/L)(π/4), which is the same as W/DABrhoL.]