A batch reactor is to be designed to treat soil contaminated with PCBs (PCBs are polychlorinated biphenyls). A test run (as a batch reactor) was performed with an initial PCB concentration of 250 mg/kg and after 10 hours the concentration declined to 50 mg/kg. Assuming zero-order kinetics, determine the time required to reduce the PCB concentration to 10 mg/kg. The soil is treated as a slurry so you can treat this as a homogeneous reaction.