An Overview of the Factors affecting Equilibrium Constant

The equilibrium constant of a chemical reaction is equal to the value of its reaction quotient at chemical equilibrium, a state attained by a dynamic chemical system after a sufficiently long period of time has passed in which its composition exhibits no discernible tendency to change further. The equilibrium constant is independent of the initial analytical concentrations of the reactant and product species in the mixture for a given set of reaction conditions. Thus, given a system’s starting composition, known equilibrium constant values can be utilized to determine the system’s equilibrium composition. However, reaction characteristics such as temperature, solvent composition, and ionic strength can all have an effect on the equilibrium constant’s value.

A working knowledge of equilibrium constants is required to comprehend a wide variety of chemical systems and biological processes such as oxygen transport via haemoglobin in the blood and acid–base balance in the human body.

Factors Affecting the Equilibrium Constant

Concentration, pressure, and temperature all have an effect on a reaction’s equilibrium position, and a catalyst has an effect on reaction speeds.

Changing concentration:

• Increasing or decreasing the concentration of a reactant or product favours one of the reactions (forward or reverse).
• This shift in reaction rate mitigates the effect of the alteration and restores the reactant-product concentration ratio. There will simply be an increase in the number of reactants and products.
• Kc will remain the same.

Changing Pressure

• Changing the system’s pressure alters the ratio of reactant to product concentrations.
• The equilibrium then moves in such a way that the effect of the change is minimised and the ratio between reactant and product concentrations is restored.
• Kc will remain the same.

Adding a catalyst to the System

• The rates of both forward and reverse reactions are increased.
• As a result, the ratio of reactant to product concentrations will remain constant.
• Kc will remain the same.

Changing Temperature

• Temperature changes favour either endothermic or exothermic reactions.
• The ratio of reactants to products will fluctuate.
• Kc will Change.

Factors Affecting Chemical Equilibrium

Chemical equilibrium is the state of a system in which neither the reactant nor the product concentrations vary over time, nor do the system’s attributes change. When the forward reaction’s rate equals the reverse reaction’s rate, the system has reached chemical equilibrium.

In chemical equilibrium, the forward reaction’s rate is equal to the backward reaction’s rate. As such, it refers to the condition of a system in which the concentrations of the reactant and product do not fluctuate over time.

After that, the system’s attributes will cease to vary and will become constant. When the concentrations of reactants and products do not vary due to equal rates of forward and reverse reactions, the system is said to be in dynamic equilibrium.

Change in Concentration

When the concentration of any of the reactants or products in an equilibrium reaction is changed, the composition of the equilibrium mixture changes to mitigate the effect of the concentration change. According to the principle of Le-Chatelier,

• The reaction that consumes the introduced substance lowers the concentration of the reactants or products.
• The reaction in the direction of replenishment decreases the concentration of reactants or products eliminated.

As a result of raising the concentration of one or more of the reactant species, the equilibrium shifts forward, resulting in the production of more products. When one or more of the product species’ concentrations are increased, the equilibrium shifts backward, resulting in the production of more reactants. Thus, as the concentration of the reactant or product is modified, the composition of the mixture changes.

Change in Temperature

According to Le-principle, Chatelier’s when an equilibrium system’s temperature is increased, i.e. when heat is supplied, the equilibrium will move in the direction of the extra heat. As the temperature rises, the equilibrium will shift toward an endothermic process. On the other hand, a reduction in temperature shifts the balance in favour of heat production, favouring exothermic reactions. According to Le-principle, Chatelier’s the influence of temperature on chemical equilibrium is dictated by the sign of the reaction’s ΔH.

• The equilibrium constant of an exothermic reaction reduces as the temperature increases.
• An endothermic reaction’s equilibrium constant increases as the temperature rises.
• Temperature fluctuations, in addition to the equilibrium constant, affect the rate of reaction.

Change in Pressure

The volume varies, resulting in a shift in pressure. Due to the fact that the total quantity of gaseous reactants and products has changed, a change in pressure can have an effect on the gaseous reaction. If the number of moles of gaseous reactants and products remains constant, pressure has no effect on the equilibrium. According to Le Chatelier’s principle, pressure changes in liquids and solids can be ignored in heterogeneous chemical equilibrium since the volume of a solution is nearly independent of pressure. As a result, the volume shift has the following effect on the equilibrium:

When pressure is increased, the reaction reverses due to the decrease in the amount of moles of gas on the reactant’s side.

When the pressure is reduced, the reaction advances due to the decrease in the amount of moles of gas on the product side.

Change in Volume

Because an increase in pressure results in a decrease in volume, the effect of a change in volume is the inverse of the effect of a change in pressure. As a result, the volume change affects the equilibrium in the following way:

• When the volume of an equilibrium gaseous mixture is diminished, the equilibrium shifts toward a smaller number of gaseous molecules.
• When the volume of an equilibrium gaseous mixture is raised, the equilibrium shifts in favour of a greater number of gaseous molecules.

Effect of a Catalyst

The catalyst has no effect on the equilibrium. This is because the catalyst is equally favourable to forward and backward reactions. As a result, the forward-to-reverse rate ratio remains constant, and the proportional amount of reactants and products present at equilibrium remains fixed. As a result, the equilibrium position is unaffected by a catalyst.

As a result, the chemical equilibrium is unaffected by the catalyst. It only accelerates the rate of a reaction. In general, a catalyst accelerates both forward and reverse reactions. As a result, the process achieves equilibrium more rapidly.

At equilibrium, whether catalysed or uncatalyzed, the same number of reactants and products will be present. A catalyst only facilitates the reaction by allowing it to proceed through a lower-energy transition state of reactants to products.

Conclusion

Chemical equilibrium refers to the situation in which the concentrations of both reactants and products do not tend to fluctuate over time during a chemical process. When the rate of forward and reverse reactions is equal, a chemical reaction is said to be in chemical equilibrium. Additionally, because the rates are equal and there is no net change in the reactant and product concentrations, the condition is referred to as dynamic equilibrium, and the rate constant is referred to as the equilibrium constant.