The document discusses factors that affect the rate of chemical reactions, including: 1) The nature and concentration of reactants - more active and concentrated reactants lead to faster reactions. 2) Surface area - greater surface area of reactants means more chances for molecular contact and a faster rate. 3) Temperature - higher temperatures increase molecular collisions and double the reaction rate with every 10K increase. 4) Catalysts - catalysts speed reactions by lowering activation energy without being used up in the reaction. Characteristics and types of catalysts are described.

23. NAME
DETAILS
Nature of reactant
 More active reactants give fast rate of reaction.
 No. of electrons present in innermost shell affects
the reactivity of reactant.
 Elements of IA are more reactive than IIA.
 Neutralization reactions and decomposition
reactions are very fast.
 Oxidation reduction reactions are slower.
 Ionic reactions are very fast.
Concentration of reactant
 Reaction is due to effective collision of reactant
molecule.
 Greater concentration of reactants more effective
collision, thus rate of reaction will high.
 In case of reactants in gases, their concentration is
increased by increasing their partial pressures.
 Rate of reaction is directly proportional to
concentration of reactants.
 Sometime concentration of reactant become
double and rate of reaction increases for four
times.

25. Surface area
 Greater surface area, greater will be chance of
contact of molecules.
 Greater surface area of molecules, greater will
be rate of reaction.
Light
 Light travel in the form of photons.
 Photons have energy depending on frequency of
light.
 Light gives the energy to reactants to form
activated complex in minimum time.
 Light increases the rate of reaction.
Temperature
 Rate of reaction is proportional to no. of collision
of molecules, this is called collision theorem.
 By increasing temperature, the no. of collisions of
molecule increases.
 Rate of reaction increases by increase in
temperature of reaction.
 By increasing temperature by 10K, the of reaction
becomes doubled.
 Arrhenius equation: K = AE
–Ea / RT the effect of
temperature on rate of reaction.

26. • CHARACTERISTICS OF CATLYST
•
• Catalyst remains unchanged.
• Catalyst is more effective when it is in finally divided powder form.
• Catalyst should not affect chemical equilibrium state of reaction.
• Catalyst cannot start a reaction; it only lowers the energy of
activation.
• Catalyst are specific in their nature.
• Temperature affects the rate of catalyst. Temperature may decrease
the volume of finally powdered catalyst.
• Catalyst poisoning occur when any foreign particle involve in
reaction.
• Addition of impurity in catalyst is called poisoning of catalyst.
•
• It may be
•
– Permanent poisoning.
– Temporary poisoning.

30. • ACTIVATION OF CATALYST
•
• Substance that increases the activity of catalyst is called promoter
or activators or catalyst for catalyst.
•
• Example:
•
• Cu promotes activity of Ni in hydrogenation of oil.
• When a substance reduces the rate of reaction then it is called
inhibitor or negative catalyst.
• In some reactions, products formed act as catalyst called
autocatalysis.
• Example:
• Hydrolysis of ester gives acetic acid which act as catalyst.
• Cu reacts with HNO3 acid produce HNO2 which act as catalyst.

31. • ENZYME CATALYSIS
• Enzymes are biocatalytical proteins, which increase the rate of biochemical
reactions.
• The substance on which enzyme an attack is called substrate.
• The point through which an enzyme attacks on substrate called active site.
• Each enzyme has its own active site.
• Specificity of substrate is present in enzyme.
• Enzyme and substrate forms enzyme – substrate complex, which then converts
into product.
• The name of enzyme usually ends on “ase”.
• Examples:
– Urease.
– Zymase.
– Dehydrogenase.
– Hydrolase.
– Maltase.
• CHARACTERISTICS OF ENZYME CATALYSIS•
• Enzymes lower the energy of activation.
• Enzymatic reactions has maximum rate at optimum temperature.
• pH of media affects the activity of enzyme.
• Using co – enzyme can increase activity of enzyme.