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A liquid-phase chemical reaction A --+ B takes place in a
Chapter 4, Problem 4.2(choose chapter or problem)
A liquid-phase chemical reaction A --+ B takes place in a well-stirred tank. The concentration of A in the feed is CAD (mol/rn3 ), and that in the tank and outlet stream is CA (moUm3 ). Neither concentration varies with time. The volume of the tank contents is V (m3 ) and the volumetric flow rate of the inlet and outlet streams is v(m3/s). The reaction rate (the rate at which A is consumed by reaction in the tank) is given by the expression r(mol A consumed/s) = kVCA where k is a constant. 156 Chapter 4 Fundamentals of Material Balances (a) Is this process continuous, batch, or semibatch? Is it transient or steady-state? (b) What would you expect the reactant concentration CA to equal if k = a(no reaction)? What should it approach if k -- 00 (infinitely rapid reaction)? (c) Write a differential balance on A, stating which terms in the general balance equation (accumulation = input + generation - output - consumption) you discarded and why you discarded them. Use the balance to derive the following relation between the inlet and outlet reactant concentrations:
Questions & Answers
QUESTION:
A liquid-phase chemical reaction A --+ B takes place in a well-stirred tank. The concentration of A in the feed is CAD (mol/rn3 ), and that in the tank and outlet stream is CA (moUm3 ). Neither concentration varies with time. The volume of the tank contents is V (m3 ) and the volumetric flow rate of the inlet and outlet streams is v(m3/s). The reaction rate (the rate at which A is consumed by reaction in the tank) is given by the expression r(mol A consumed/s) = kVCA where k is a constant. 156 Chapter 4 Fundamentals of Material Balances (a) Is this process continuous, batch, or semibatch? Is it transient or steady-state? (b) What would you expect the reactant concentration CA to equal if k = a(no reaction)? What should it approach if k -- 00 (infinitely rapid reaction)? (c) Write a differential balance on A, stating which terms in the general balance equation (accumulation = input + generation - output - consumption) you discarded and why you discarded them. Use the balance to derive the following relation between the inlet and outlet reactant concentrations:
ANSWER:Problem 4.2
A liquid-phase chemical reaction 
where k is a constant.
(a) Is this process continuous, batch, or semibatch? Is it transient or steady-state?
(b) What would you expect the reactant concentration 
(c) Write a differential balance on A, stating which terms in the general balance equation (accumulation = input + generation - output - consumption) you discarded and why you discarded them. Use the balance to derive the following relation between the inlet and outlet reactant concentrations:
Verify that this relation predicts the result in part (b).
Step by Step Solution
Step 1 of 3
a) For a chemical reaction the branch of chemistry dealing with the speed as well as the rate of reaction is known as Reaction kinetics. Reaction Kinetics is also known as Chemical kinetics. It is that branch of physical chemistry that is concerned with understanding the rates of chemical reactions.
So, the given reaction is Continuous (product is continuously removed and reactant is continuously added) and also Process is steady state ("neither concentrations vary with time").