Simple eutectic system(pb ag)

Simple eutectic system- quick overview

1. SIMPLE EUTECTIC SYSTEM AND ENZYME CATALYSIS By-ANEETTA DAVIS M15NT01

2. SIMPLE EUTECTIC SYSTEM (Pb and Ag system)

3. SIMPLE EUTECTIC SYSTEM Eutectic comes from a Greek word EUTEKTOS EU TEKTOS GOOD MELTING EASILY MELTING

4. Two Component System 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. 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. If 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 Lead and silver are completely miscible in liquid state. 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+SOLID Ag LIQUID + SOLID Pb EUTECTIC + 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 system

8. ENZYME CATALYSIS

9. Catalysts Catalysis The substance that can alter The phenomenon or the rate of a reaction. process is called catalysis.

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 Enzymes are typically HUGE proteins, yet only a small part are actually involved in reaction. The active site has two basic components. catalytic site binding site

14. Catalytic site Where reaction occurs Binding Site holds substrate in place Substrate Enzyme The Active Site

15. CATALYTIC POISONING 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

16. AUTOCATALYSIS 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.

17. THEORIES OF CATALYSIS The two main theories of catalysis are; Intermediate compound formation theory Adsorption theory

18. INTERMEDIATE COMPOUND FORMATION THEORY A + [CATALYST] [INTERMEDIATE] [INTERMEDIATE] + B PRODUCT + CATALYST 2SO 2 + O 2 [NO] 2SO 3 Example: 2NO + O 2 2NO 2 NO 2 + SO 2 SO 3 + NO

19. ADSORPTION THEORY A (g) + B (g) C (g) + D (g) CATALYST B A A B A - - ->B C D

20. THEORIES OF ENZYME CATALYSIS The two main theories of enzyme catalysis are: Lock and key model Induced fit model

21. 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.

22. INDUCED FIT MODEL Active site may not fit substrate. Site must change in order to form the complex.