Oscillation

Oscillation is the repetitive variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but is sometimes used as a synonym of "oscillation". Oscillations occur not only in physical systems but also in biological systems, from human society to the brain.

Oscillation

By Zaib Abbasi 22:30

Definition of Dynamic Equilibrium

Dynamic equilibrium is the state of a reversible reaction where the forward reaction rate is equal to the reverse reaction rate, resulting in no observable net change in the system. Reactions are continuing to proceed in the forward and reverse direction dynamically; however, there is no net change in the amount of product or starting material. Dynamic equilibrium is also called steady state. In the early stage of a reversible reaction, the forward reaction proceeds more quickly than the reverse until the equilibrium state is reached when the forward and reverse rates are equal. An example of an important dynamic equilibrium is the equilibrium between ice and water at 0 ºC, where ice is melting at the same rate as the water is freezing.

Definition of Dynamic Equilibrium

By Zaib Abbasi 23:09

Law of Mass Action

Law stating that the rate of any chemical reaction is proportional to the product of the masses of the

reacting substances, with each mass raised to a power equal to the coefficient that occurs in the chemical equation. This law was formulated over the period 1864–79 by the Norwegian scientists Cato M. Guldberg and Peter Waage but is now of only historical interest. This law was useful for obtaining the correct equilibrium equation for a reaction, but the rate expressions it provides are now known to apply only to elementary reactions. By the term active mass we mean the molar concentration,or number of moles per dm3 in a dilute solution.


a A + b B --> c C + d Dwhere a, b, c, d are the coefficients for a balanced chemical equation.

The mass action law states that if the system is at equilibrium at a given temperature, then the following ratio is a constant.

[C]c [D]d ------------- = Keq [A]a [B]b

The square brackets "[ ]" around the chemical species represent their concentrations. This is the ideal law of chemical equilibrium or law of mass action.The units for K depend upon the units used for concentrations. If M is used for all concentrations, K has units

M^c+d-(a+b)

Accordin to law of Mass Action

the rate of forward reaction is proportional to [A] [B],while the rate of reserve reaction is equal to kr [C] [D] where kf and kr are the rate of constant for the forward and reverse reactions,respectively

Law of Mass Action

By Zaib Abbasi 10:13