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Catalysis as Phenomenon Catalysis and Chemical Engineering / L2 Lecture 2 / Outline Outline Catalysis and Chemical Engineering / L2 Formal Chemical Kinetics 1. The Main Law of Chemical Kinetics. Chemical Kinetics – Laws and Principles. The ‘Active Masses’ Breakthrough. 2. Reaction in Progress. Characteristics and Terms. Rate of Reaction – what? and when? 3. ‘Simple Math’ in Chemical Kinetics. Reactions of ‘Simple Types’. 4. Formal Kinetics of Complex Reactions. ‘Simplest Complexity’ – Consecutive, Parallel, Reversal Reactions. Three Basic Principles of Chemical Kinetics. Catalysis as Phenomenon Catalysis and Chemical Engineering / L2 Part 1. The Main Law of Chemical Kinetics Laws and Principles - ??? Laws and Principles Catalysis and Chemical Engineering / L2 The Nature of Scientific Laws – ontology or epistemology ? i.e. goal or instrument ??? Nature vs. Science Nature: Science: objects and phenomena HUMAN ACTIVITY !!! Laws and Principles Catalysis and Chemical Engineering / L2 The Nature of Scientific Laws – ontology or epistemology ? i.e. goal or instrument ??? Nature vs. Science Nature: Science: objects and phenomena comprehension Methodology: development of Models Scientific Laws – models of Objects and Phenomena that reflect the current level of their comprehension Laws and Principles Catalysis and Chemical Engineering / L2 The Nature of Scientific Laws – ontology or epistemology ! i.e. goal or instrument – BOTH !!! Nature vs. Science Nature: Science: objects and phenomena comprehension Methodology: development of Models Scientific Laws – models of Objects and Phenomena that reflect the current level of their comprehension Laws and Principles Catalysis and Chemical Engineering / L2 Scientific Laws – models of Objects and Phenomena that reflect: (i) the current level of their comprehension; (ii) stable (repeatable, reproducible) relation(ship)s between them ⇒ based on practice (observations, experiment, etc.) Principles – also based on practice ‘tools of knowledge’, but sublimed to the level of ‘common sense’, i.e. higher degree of generalization than laws. Any scientific discipline (including Chemical Kinetics) operates both laws and principles Reactivity Reactivity – Catalysis and Chemical Engineering / L2 the ability of the given substance to undergo certain transformation(s) in particular conditions ⇒ qualitative & quantitative characteristic Example. Esterification of alcohols (Menshutkin reaction) Nikolai Aleksandrovich Menshutkin (1842-1907) Conditions: temperature, solvent & additives, concentrations, mixing, etc. Reactivity Reactivity – Catalysis and Chemical Engineering / L2 the ability of the given substance to undergo certain transformation(s) in particular conditions ⇒ qualitative & quantitative characteristic Description, Example. Esterification of alcohols (Menshutkin reaction) i.e. quantitative relationships ??? Nikolai Aleksandrovich Menshutkin (1842-1907) Conditions: temperature, solvent & additives, concentrations, mixing, etc. Catalysis as Phenomenon Catalysis and Chemical Engineering / L2 Active Mass Breakthrough Active Mass … Catalysis and Chemical Engineering / L2 Cato M. Guldberg and Peter Waage (1864-67 г.): When two reactants, A and B, react together at a given temperature in a ‘substitution reaction’, the affinity, or chemical force between them, is proportional to the active masses, [A] and [B], each raised to a particular power: affinity = α [A]a [B]b a A + b B → product(s) [A], [B] – ‘active masses’, or concentrations of reactants; a, b – corresponding stoichiometric coefficients Active Mass … Catalysis and Chemical Engineering / L2 The rate of one-side stoichiometric isothermal reaction a A + b B + c C + … → a’ A’ + b’ B’ + c’ C’ + … is proportional to the product of reactant concentrations built in the degree equal to the corresponding stoichiomentric coefficients. In the general case: or Active Mass … Catalysis and Chemical Engineering / L2 If reaction can proceed in both directions, i.e. aA + bB + cC + … a’ A’ + b’ B’ + c’ C’ + … the state called equilibrium may take place, in which the rates in both directions are equal and Active Mass … kinetic control Catalysis and Chemical Engineering / L2 thermodynamic control