Chemical Kinetics

Question 1

Factors influencing the rate of chemical reactions

Answer 1

1. Concentration of the reacting species
2. Temperature of the system
3. Nature of reactants and products
4. Presence of a catalyst
5. Surface area
6. Exposure to radiation

Question 2

How does concentration of reactant affect rate of reaction

Answer 2

Rate of reaction is directly proportional to the concentration of reactants

Question 3

How does temperature affect rate of reaction

Answer 3

In general, an increase in temperature leads to increase in rate of reaction

Rate of reaction becomes almost double for every 10K rise in temperature

Question 4

How does nature of reactants and products affect rate of reaction

Answer 4

The rate of reaction is faster in case of a more reactive metal than a less reactive metal. For example, sodium, being highly reactive, reacts violently with cold water while calcium does not react with cold water at all.

Question 5

How does presence of a catalyst affect rate of reaction

Answer 5

A catalyst offers a separate reaction pathway where activation energy is lower.

see graph

Question 6

How does surface area infuence the rate of reaction

Answer 6

Larger the surface area of the reactants, more is the rate of reaction

Question 6

How does exposure to radation affect rate of reaction

Answer 6

The photons present in such radiations have sufficient frequency to break certain bonds in the reactant molecules

Question 7

Rate constant formula

Answer 7

mol^(1-n) L^(n-1) s^-1

Question 8

Law of mass action

Answer 8

At a given temperature the rate of chemical reaction is directly proportional to the product of the molar concentration of the reactants

Question 9

Order of a reaction

Answer 9

The sum of the powers to which the concentration terms are raised in the rate law equation to express the observed rate of reaction

Question 10

Half life of a reaction

Answer 10

Time taken for half of the reaction to be completed is called half-life

Question 11

Temperature coefficient

Answer 11

Ratio of rate constant of a reaction at two different tempertures separated by 10^oC

Question 12

What does collision theory say

Answer 12

For reactants to collide and form products:
1. Threshold energy
2. Proper orientation

Question 13

Threshold energy

Answer 13

Minimum amount of energy which the reactant molecules must posses to have proper collision and form products

Question 14

Activation energy

Answer 14

Maximum energy required by reactants to undergo chemical reaction

If activation energy is low, large no. of molecules are able to cross the energy barrier and rate of reaction is high

Question 15

Arrhenius equation

Answer 15

Quantitative dependence of rate of reaction on temperature