Question

Define or explain the following terms. a) Equilibrium constant expression - b) Equilibrium constant - c) Absorbance - d) Beer's Law -

Answer 1

Explanation:

(a) Equilibrium constant expression is ratio of concentrations of products over reactants each raised to their power of stoichiometric coefficients.

For example consider an equilibrium which is:

$aA+bB\rightleftharpoons cC+dD$

The expression is:

$K_c=\frac {[C]^c[D]^d}{[A]^a[B]^b}$

(b) Equilibrium constant of the chemical reaction is value of the reaction quotient of the reaction at the stage of chemical equilibrium which is a state that is approached by the dynamic chemical system at which the composition of the reactant and the product has no measurable tendency towards the change.

(c) Absorbance is the measure of capacity of the substance to absorb the  light of a specific wavelength. Absorbance is equal to the logarithm of reciprocal of transmittance.

(d) The Beer's law relates attenuation of the light to properties of material through which light is travelling.

The expression for the law is:

A = ε × l× c

Where,

A is the absorbance

ε is molar absorptivity coefficient

l is the path length

c is the concentration.