Kinetics

Kinetics is a term used in the branch of mechanics defining the relationship between the motion of bodies and its causes- forces and torques. Any power that makes a body to undergo change in speed, direction or shape is known as force. The tendency of a force to rotate an object on fulcrum is known as torque. According to engineering mechanics kinetics can be defined as the relation between external forces and their kinematic variables. The study related to continuum in velocity space is referred as kinetics in plasma physics. The term kinetics is used to refer chemical kinetics, physical kinetics, and crystal growth kinetics.

Chemical Kinetics (Reaction kinetics)

The study of rates of chemical processes is known as chemical kinetics. The influence of experimental conditions on the speed and yield of a chemical reaction is investigated in kinetics. Reaction rates are determined in chemical kinetics and using these rates, rate laws and rate constants are derived. Chemical kinetics is pioneered and developed by Peter wage and Cato Goldberg by developing the “law of mass action” (According to the law speed of chemical reaction is proportional to the quantity of substances reactants).  The major factors that influence the rate of reactions are concentration of reactants, nature of reactants, pressure, temperature and catalysts.

Factors affecting Rate of reactions

The rate of any reaction varies depending upon the nature of reactants. Reactions will be fast in acid, base reactions. Reactions involving formation of salts and ion exchange are fast reactions. The reaction will be very slow if covalent bond formation takes place in the reaction. Rate of reaction will be greater if it involves less arrangement of bonds. When the reactants are in same phase the reaction will take place more rapidly. But if the reactants are in different phases the reaction will be limited. The greater the surface area of contact of reactants, the faster the reaction will be. When the concentration of reactants is increased, the rate of reaction also increases. Rate of chemical reactions are greatly affected by temperature. Thermal energy will be high in molecules with high temperature and this helps the reaction to continue faster. Any substance that accelerates the rate of reaction, remaining chemically unchanged is known as a catalyst. It provides various reaction mechanisms with lower activation energy and thus increases the rate of reaction .When pressure is increased in a gaseous reaction, the number of collisions between them increases and thus increases the rate of reaction.

Questions:

• Define chemical kinetics?
• What are the various factors affecting rate of reaction?