(6 pts.) The following gas phase reaction system is conducted in an isothermal constant volume batch reactor. The reactor is charged with pure A with an initial concentration CAO AB ri = k CA B D r2 = K2 CB (3 pts.) Using the pseudo steady state approximation, derive an expression for the concentration of B in terms of CA. Do not solve for the exact form of CA(t). (3 pts.) Under what condition would this approximation fail?