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In chemistry, equilibrium refers to the state that exists when the rate of a chemical reaction and its reverse reaction are equal. This term is derived from the Latin aequilbrium, which is composed of the prefix aequi- “equal” and the suffix libra “balance, scale.”
At equilibrium, the two opposing reactions occur at the same rate, or velocity, and there is no net change in the amount of chemicals involved in either process.
At this stage, the reaction can be considered complete; that is, the reaction has converted the greatest amount of reactants to products under the reaction conditions specified in the reaction design. And such concludes the reply.
The conditions that control equilibrium can be quantified.
A condition of equilibrium is considered to be stable if modest externally generated displacements from it produce forces that tend to oppose the displacement and return the body or particle to its equilibrium state.
Le Chatelier’s Principle-
Changing the reaction conditions can have an effect on the reaction’s outcome. Le Chatelier’s approach can be used to forecast the effects of these changes. It asserts that when a system in chemical equilibrium is disturbed by a change in temperature, pressure, or concentration, the system’s equilibrium composition changes in a way that tends to compensate for the disturbance.
There are four possible modifications to reaction conditions to consider:
When reactants or products are added or removed – when more products are added – the equilibrium responds by raising the amount of reagents, and vice versa.
Increasing the pressure or volume of a system – often for gas phase processes – is proportional to the net change in moles throughout the reaction, aA + bB —>cC + dD: if c+d > a+b, increasing the pressure produces fewer products, and vice versa.
Changing the system’s temperature – if the reaction is exothermic, aA + bB -> cC + dD; DH = 0 (heat is produced, not consumed), increasing T results in a decrease in the products and vice versa.
Adding a catalyst to the system has no effect.
Equations For Calculating Chemical Equilibrium
According to the law of active mass, the rate of chemical reaction is proportional to the product of the reactants’ molecular concentrations multiplied by their respective molecular powers.
When A and B are joined, the conversion rate is proportional to their concentration, shown by the symbol r1.
r1 = k1 [A] [B]
k1 is referred to as the rate constant or rate coefficient, and the square brackets denote the concentrations (mol/litre) of the compounds included in the square brackets.
As an illustration, consider the rate of conversion between C and D:
r2 = k2 × [C] × [D]
When the two rate constants are equivalent, r1 = r2, the system is stable.
k1 × [A] × [B] = k2 × [C] × [D]
Keq is the abbreviation for the equilibrium constant at a specific temperature.
Keq = [C] × [D] / [A] × [B]
This particular equation is referred to as a chemical equilibrium equation.
When reactant concentrations are expressed in moles/lit, the equilibrium constant equals Kc; when reactant concentrations are expressed in partial pressure, the equilibrium constant equals Kp.
Equilibrium’s Function in Chemical Processes-
When a chemical reaction is reversible, chemical equilibrium is established when the reactant and product concentrations remain constant.
A reversible chemical reaction is one in which the products react with the original reactants immediately after they are formed, producing the original reactants.
When the concentrations of chemical entities participating in a chemical process do not vary or cannot vary over time without external input, the term “equilibrium” is employed.
As a result, a system that is chemically balanced is said to be in a stable state.
When a chemical reaction takes place in a container that prevents any of the reactants from entering or departing, the concentrations of the various components change as some are consumed and others are generated.
It will eventually come to an end, and the composition will remain unchanged as long as the system is not disrupted.
Conclusion-
The equilibrium constant is significant because it indicates the location of the equilibrium. The bigger the equilibrium constant, the more away from the products the equilibrium is.
It is used as a refrigerant, for water purification, and in the production of polymers, explosives, textiles, insecticides, dyes, and other compounds. Haber’s technique produces ammonia. It employs the Le Chatelier principle to boost ammonia output.
