4. TWO COMPONENT SYSTEM
o A two component system can be defined as one
in which it is possible to express the composition
of all the phases in terms of two substances.
o In a two component system, solid – liquid
equilibria is considered as they are unaffected by
the changes in pressure; such systems are called
condensed system which are studied at one
atmosphere.
Therefore, for condensed state the phase rule
equation is F’=C-P+1
5. oIf two substances are completely miscible in liquid
state but immiscible in solid state forms a simple
eutectic system.
The mixture that has the lowest melting point is called
eutectic mixture and the temperature at which it
crystallizes as a whole is called eutectic temperature.
6. LEAD AND SILVER SYSTEM
o Lead and silver are completely miscible in
liquid state.
o Molten Pb and Ag are miscible in all
proportion a homogenous solution is
produced. The four possible phases are:
Solid Ag
Solid Pb
Solution(Ag + Pb)
Vapor
7. A
O
B
L N
LIQUID
MELT
(Pb+Ag)
LIQUID+SOLI
D Ag
LIQUI
D +
SOLID
Pb
EUTECTI
C +
SOLID Pb
EUTECTIC +
SOLID Ag
Composition
Temperature
327
303
Freezing or melting
point curve of lead
961
Freezing point or
melting point curve of
silver
Eutectic point
2.5% Ag and 97.5% Pb
The phase diagram for Pb-Ag
10. PROPERTIES OF CATALYSTS
It alters the rate of reaction.
It remains unchanged in mass and
chemical composition after the completion
of the reaction.
A small amount is enough to bring about a
reaction between large reactants.
It is very specific.
11. TYPES OF CATALYSIS
CATALYSIS
Homogenous Heterogeneous
The catalysts and
reactants are in the
same phase.
The catalysts and
reactants are in different
phases.
12. ENZYME CATALYSIS
Enzyme is a biological catalyst which is a
protein.
The increase in the rate of a chemical
reaction by the active site of a protein is
called enzyme catalysis.
13. THE ACTIVE SITE
o Enzymes are typically HUGE proteins, yet
only a small part are actually involved in
reaction.
o The active site has two basic components.
catalytic site
binding site
16. CATALYTIC POISONING
o It is the substance that reduces the
effectiveness of a catalyst in a chemical
reaction.
Example:
Carbon on silica-alumina catalyst in the
cracking of petroleum
17. AUTOCATALYSIS
o If one of the reaction products is also a
reactant and therefore a catalyst in the same
reaction then the chemical reaction is said to
be autocatalytic.
18. THEORIES OF CATALYSIS
o The two main theories of catalysis are;
Intermediate compound formation theory
Adsorption theory
19. INTERMEDIATE COMPOUND FORMATION
THEORY
A + [CATALYST] [INTERMEDIATE]
[INTERMEDIATE] + B PRODUCT +
CATALYST
2SO2 + O2
[NO]
2SO3
Example:
2NO + O2 2NO2
NO2 + SO2 SO3 + NO
21. THEORIES OF ENZYME CATALYSIS
o The two main theories of enzyme catalysis
are:
Lock and key model
Induced fit model
22. LOCK AND KEY THEORY
This model was given my Emil Fischer.
Enzyme is “lock” and Substrate is the “key”.
Substrate structure
must fit into enzyme’s structure.
23. INDUCED FIT MODEL
Active site may not fit substrate.
Site must change in order to form the complex.
Hinweis der Redaktion
Catalytic site = Where the reaction actually occurs.
Binding site = Area that holds substrate in proper place. Enzymes uses weak, non-covalent interactions to hold the substrate in place based on R groups of amino acids. Shape is complementary to the substrate and determines the specificity of the enzyme. Sites are pockets or clefts on the enzyme surface.