Factors Affecting Chemical Equilibrium

In a chemical reaction, there are always different numbers of atoms and molecules present. There are some rules about how these numbers should change when you mix chemicals. For example, if two gases combine, then the total amount of gas must stay the same. That means the number of molecules in the mixture stays the same. This is known as a chemical equilibrium.

Factors Affecting Chemical Equilibrium

Temperature, pressure, and concentration all affect the state of equilibrium in a system. Change to any of them, or change how much of each there is, and you’ll see equilibrium being disrupted. Equilibrium is restored when everything goes back to normal.

The principle of Le Chatelier is an observation regarding the chemical equilibria of processes. It asserts that changes in a system’s temperature, pressure, volume, or concentration will cause predictable and opposing changes in order to attain a new equilibrium state. In practice, Le Chatelier’s approach may be utilised to understand reaction circumstances that encourage enhanced product production.

Changes in concentration

When adding an extra ingredient to a reaction, the equilibrium is shifted to the right (towards the right side). You can also reduce the concentration of any ingredient or remove it entirely. this will shift the equilibrium to the left, towards the original starting point.

The opposite is also true. When we add more product to a system, the equilibrium shifts to the left to create more reactants. Alternatively, removing reactants from the system causes equilibrium to shift to the left.

Reversible reactions are self-corrective. When they are put out of equilibrium by changes in concentrations, temperatures, or pressures, the system will automatically correct itself.

The equilibrium of this process, in which carbon monoxide and hydrogen gas combine to generate methanol, exemplifies this:

CO + 2H2 ⇌ CH3OH

Assume we raise the concentration of CO in the system. According to Le Chatelier’s principle, the amount of methanol will grow, reducing the overall change in CO. If we add a species to the total reaction, the response will benefit the side opposing the species addition.

Changes in pressure

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

• The reaction reverses as the pressure is increased because the amount of moles of gas on the reactant’s side decreases.
• Because the amount of moles of gas on the product’s side decreases as the pressure is dropped, the reaction progresses.

Addition of an inert gas

Constant volume addition of inert gas- When a constant volume of inert gas is introduced to the equilibrium system, the total pressure rises. Reactant and product concentrations, on the other hand, will stay constant. As a result, under these conditions, there will be no influence on the equilibrium. The number of moles per unit volume of various reactants and products will drop. As a result, the equilibrium will change in favor of increasing the number of moles of gas.

Changes in temperature

 As the temperature rises, the equilibrium will shift toward an endothermic process. Temperature reduction, on the other hand, shifts the balance in the direction of heat generation, favouring exothermic processes. According to Le Chatelier’s principle, the influence of temperature on chemical equilibrium is defined by the sign of H in the reaction.

The heat of reaction is what determines the influence of temperature on equilibrium. Remember that in an endothermic process, heat is absorbed, and the value of H is positive. Thus, heat may be viewed as a reactant in an endothermic reaction:

Heat + A ⇌ B ; ΔH = positive

The scenario is exactly the reverse for an exothermic process. As heat is produced during the reaction, it is a product. Thus the value of H is negative:

A ⇌ B + heat  ; ΔH = negative

If we consider heat to be a reactant or a product, we can use Le Chatelier’s principle in the same way that it is done for increasing or decreasing concentrations. For example, increasing the temperature of an endothermic reaction is effectively the same as adding additional reactants to the system, and so, according to Le Chatelier’s principle, the equilibrium will move to the right. Reducing the temperature on an endothermic reaction, on the other hand, will move the equilibrium to the left because lowering the temperature is equal to eliminating a reactant in this situation.

Effect of a Catalyst:

A catalyst only speeds up a reaction and does not influence the chemical equilibrium. It equally speeds up both the reverse and the forward reactions. This influences the reaction to attain its equilibrium faster. The same number of products and reactants are present at equilibrium in a catalysed and uncatalysed reaction. The presence of a catalyst only stimulates the reaction to proceed through a low-energy transition state of reactants to products.

Conclusion

The system’s temperature, pressure, and concentration are all factors that influence equilibrium. When one of these components changes, the system’s balance changes, and the system readjusts itself until it regains equilibrium. The parts that follow go through some of the most important elements that influence equilibrium.