The 6-Step Problem-Solving Framework
A universal skeleton for every reactor problem in CN2105. Click a step to explore.
Read the problem ā what do you have?
Before writing a single equation, read the problem and answer five classification questions. Your answers here determine the EXACT form of every equation in every later step. This is like choosing which recipe to follow before you start cooking ā get this wrong, and everything downstream is wrong.
A reactor is simply a container where a chemical reaction happens. In CN2105, there are three idealized reactor types, each with a different assumption about mixing.
A sealed container ā nothing goes in or out during the reaction. Think of a pressure cooker: you seal it, the reaction runs for some time, then you open it. The key variable is TIME. You ask: "how much has reacted after t minutes?"
An open tank with a stirrer, where fresh material continuously flows in and product continuously flows out. Because the stirrer keeps everything perfectly mixed, the concentration EVERYWHERE inside the tank is identical to the concentration at the outlet. This is the critical CSTR assumption.
A long tube where fluid flows through like a plug ā no mixing in the flow direction. Concentration changes gradually along the length of the tube. The key variable is VOLUME (or equivalently, position along the tube).
Multiple reactors connected together. In series: the outlet of one reactor feeds into the next. In parallel: the feed splits into multiple reactors. You solve each reactor individually using the same method.
Q1.For a first-order irreversible reaction A ā B in a steady-state CSTR, the design equation gives conversion X as: