Download Catalysis and Chemical Engineering / L2

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