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Chemical Equilibriu
Chemical equilibrium is the state of equilibrium between various chemical species existing in the same or different phases. Chemical equilibrium can be divided into two categories.
(1) Homogeneous equilibrium: Homogeneous equilibrium reactions are equilibrium reactions in which all of the reactants and products are in the same phase.
Example
N2+3H2=2NH3
(2)Heterogeneous equilibrium: Heterogeneous equilibrium reactions are equilibrium reactions in which the reactants and products are present in distinct phases.
Example
CaCO3=CaO+CO2
Types Of Reaction
There are two types of reactions: reversible and irreversible.
When the concentration of reactants declines and the concentration of products increases over time, a chemical reaction has occurred. Chemical reactions are divided into two categories based on the extent to which they progress:
(1) Reversible reactions: Reversible reactions are those in which only a portion of the entire amount of reactants is transformed into products.
Reversible reactions’ characteristics
(a) These reactions can begin on either side of the equation.
(b) These reactions are never fully developed.
(c) These reactions have a proclivity for achieving equilibrium.
(d) The reversibility of the reaction is shown by this sign ().
(e) In a reversible reaction, the free energy change is zero (DG = 0).
2) Irreversible reactions: Irreversible reactions are those in which the complete amount of the reactants is transformed into products.
Irreversible reactions’ characteristics
(a) These reactions only have one direction of action (forward direction),
(b) These reactions can be carried out to completion.
(c) An arrow () is drawn between the reactants and the products.
(d) In an irreversible process, DG is < zero
Equilibrium Constant
(1) Law of chemical equilibrium in terms of the law of mass action: The law of mass action can be applied to a reversible reaction to create a mathematical formula for the equilibrium constant.
Consider the following simple reversible reaction: A + B= X + Y, in which the reactants (A and B) and products (X and Y) are in equilibrium (X and Y). The initial response is,
X + Y = A + B
The law of mass action states that
[A][B]= kf[A][B]
Where [A] and [B] are the molar concentrations of reactants A and B, respectively, and kf is the forward reaction rate constant.
In the same way, the reverse response is X + Y=A + B.
[X][Y] = kb[X][Y]
Where [X] and [Y] are the molar concentrations of products X and Y, respectively, and kb is the rate constant for the backward reaction.
When two opposing reactions reach equilibrium, their rates become equal. As a result, when everything is in balance,
Forward reaction rate Equals backward reaction rate
kb[X][Y] = kf[A][B]
kf/kb=[X][Y]\[A][B]
The equilibrium constant, which is equal to kf/kb and has a constant value for a reaction at a given temperature, is called K. This is the law of chemical equilibrium .
At a constant temperature, the ratio of the products’ molar concentrations to the reactants’ molar concentrations, with each concentration term increased to a power equal to its stoichiometric coefficient in the balanced chemical equation.
Characteristics of Chemical Equilibrium
The following are the main properties of chemical equilibrium:
1.Forward and reverse reactions have the same rate in chemical equilibrium.
2.At equilibrium, all of the reactants and products are present.
3.A catalyst has no effect on the equilibrium position.
4.At equilibrium, the concentrations of the reactants and products are constant
Law Of Mass Action
“The rate of a chemical reaction at any given temperature is proportional to the product of the molar concentrations of reactants, each concentration term increased to the power corresponding to the number of molecules of the individual reactants participating in the reaction,” says the law of mass action.
aA+bB=cC+dD
The stoichiometric coefficient is the number of molecules of a reactant that participate in a reaction. In the above equation, a, b, and c…. are the stoichiometric coefficients of A, B, and C…., respectively.
Conclusion
We now know what equilibrium is in chemistry. We’ve gone over some key concepts and principles relating to reaction rates and chemical equilibrium. In chemistry, equilibrium is a state in which the concentrations of reactants and products do not fluctuate. Although there appears to be no change in equilibrium, this does not imply that all chemical reactions have ended
