An ideal continuous stirred tank reactor (cstr) has an influent containing chemical x at a concentration of 150 mg/l and a flow rate of 100 gpm (380 liters/min). chemical x undergoes a first-order decay reaction having k = 0.40 hr determine: a. the required detention time and volume of the cstr if the effluent concentration contains 20 mg/l of chemical x. express the volume in both gallons and liters. b. use a spreadsheet to perform the necessary calculations and then use the spreadsheet's graphing tools to plot two graphs; i. pollutant removal efficiency, e (defined in homework #4 problem statement), on the vertical or y-axis versus hydraulic detention time on the horizontal or x-axis. ii. effluent concentration, cxi, on the vertical or y-axis versus hydraulic detention time on horizontal or x-axis. analyze and comment on the significance of the graphs. c. how many times larger must a cstr be than a pfr to achieve 80 percent pollutant removal or conversion? d. how many times larger must a cstr be than a pfr to achieve 90 percent pollutant removal or conversion?