This lecture covers the Chemical Reaction Engineering (CRE) algorithm applied to batch reactors and CSTRs, with a focus on isothermal reactor design. Topics include mole balances, rate laws, stoichiometry, and the evaluation of reactor volumes. Examples illustrate the application of the algorithm to real-world scenarios, such as the oxidation of SO2 and the decomposition of N2O4. The instructor guides students through deriving equations for concentration as a function of conversion, solving stoichiometric tables, and calculating equilibrium conversions. Practical aspects, like cycle times for batch reactors and the determination of CSTR volumes, are also discussed.