Dynamic Equilibrium

Dynamic Equilibrium is a state of balance in which opposing forces or influences are balanced. It is a state of equilibrium in which the rate of change of a system is zero.

Dynamic Equilibrium can be defined as the state of a given system in which the reversible reaction taking place in it ceases to alter the ratio of reactants and products, but there is an ongoing movement of substances between the reactants and the products. This movement occurs at an equal rate and there is no net change of the reactant and product ratio.

A dynamic equilibrium will be established in a reversible reaction when the forward and reverse processes occur at the same rate, resulting in no observable change in the overall system. This will cause the concentrations or partial pressures of all species involved to remain constant. In other words, if we look at the fields of Physics and Chemistry, this type of equilibrium is usually seen after a reversible reaction has occurred.

Systems that are in a steady state are examples of systems that maintain a dynamic equilibrium, and the equilibrium constants for these types of equilibria are represented with the help of the rate constants for the forward and backward reactions. Equilibrium constants.

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Examples of Dynamic Equilibrium

Static vs Dynamic Equilibrium

When two opposing forces are operating simultaneously and independently of each other, two states (state 1 and state 2) are formed with the interchange between the two states. This is known as dynamic equilibrium, which is usually represented by a double-sided arrow ”A ⇌ B” in Chemistry and Physics.

Depending on the composition of the two states, two equilibriums are defined: physical equilibrium and chemical equilibrium.

⇒ Also Read:

Chemical Equilibrium

Le Chatelier’s Principle

Examples of Dynamic Equilibrium

  1. The exchange of gases between the atmosphere and oceans
  2. The balance between predators and prey in an ecosystem
  3. The balance between the rate of photosynthesis and respiration in plants

A few important examples of dynamic equilibrium in our everyday life are:

  1. The balance between supply and demand in the economy
  2. The balance between photosynthesis and respiration in plants
  3. The balance between the water cycle and evaporation in the atmosphere

When half of the aerated drink is poured out of the bottle, the liquid carbon dioxide is slowly converted into gaseous carbon dioxide. This continues until a new point of equilibrium is reached, where the rate of conversion of CO2 from gas to liquid is equal to the rate of conversion of CO2 from liquid to the gaseous phase.

The single-phase system in which acetic acid undergoes dissociation, leading to an acid-base equilibrium can be described by the following reaction:

CH3COOH ⇌ CH3COO– + H+

In the gaseous phase, the dimerization of nitrogen dioxide can be observed. Reaction: 2NO2 ⇌ N2O4

Henry’s Law can be used to explain the dynamic equilibrium of the first example provided, where the equilibrium concentration of carbon dioxide in the liquid phase is directly proportional to the partial pressure of the CO2 gas in the bottle.

Reaction of Industrial Synthesis of Ammonia via Haber’s Process:

N2 (g) + 3H2 (g) ⇌ 2NH3 (g)

Difference Between Static and Dynamic Equilibrium

Static equilibrium occurs when the sum of all forces and torques acting on a system is equal to zero, while dynamic equilibrium occurs when the sum of all forces and torques acting on a system is constant over time.

Static equilibrium refers to a condition where the reaction occurring in a system is completely halted and there is no movement between the reactants and the products corresponding to the chemical reaction.

If the forces acting on an object balance each other, in addition to the constancy of content and composition, no movement of the object takes place. This is static equilibrium.

The key differences between static and dynamic equilibrium are outlined in the table below.

| Static vs Dynamic Equilibrium |

Dynamic Equilibrium Static Equilibrium
Constant Change Constant State

| This type of equilibrium is irreversible in nature. |

| The equilibrium state indicates that the reactants and products are in a dynamic balance, with no further chemical reaction occurring. |

| In dynamic equilibrium, the forward and the backward reaction rates are equal | In static equilibrium, the forward and backward reaction rates are zero |

| It can occur in both open and closed systems | It can only occur in closed systems |

However, the resultant force acting on both of these types of equilibria in a system is zero, meaning that generally, neither of these types of equilibrium display any visible changes.

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Physical Equilibrium

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Chemical Equilibrium— title: “Dynamic Equilibrium” link: “/dynamic-equilibrium” draft: false

Dynamic Equilibrium is a state in which opposing forces or influences are balanced and remain unchanged over time.

Dynamic Equilibrium can be defined as a state in which the reversible reaction taking place in a given system has stopped changing the ratio of reactants and products, but there is still a movement of substances between the reactants and the products. This movement occurs at an equal rate and there is no net change of the reactant and product ratio.

A dynamic equilibrium will be established after the occurrence of a reversible reaction in the fields of Physics and Chemistry. This occurs when the forward and reverse processes occur at the same rate, resulting in no observable change in the overall system. Once this equilibrium is achieved, the concentrations or partial pressures of all species will remain constant.

Systems in steady states are examples of equilibria which are represented by the equilibrium constants derived from the rate constants of the forward and backward reactions.

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Examples of Dynamic Equilibrium

Difference Between Static and Dynamic Equilibrium

When two forces are operating independently and simultaneously, two states (state 1 and state 2) are formed with an interchange between them. This is known as dynamic equilibrium, and is usually represented by a double-sided arrow, such as “A ⇌ B”, in Chemistry and Physics.

Depending on the composition of the two states, two equilibriums are defined: physical equilibrium and chemical equilibrium.

⇒ Also Read:

Chemical Equilibrium

Le Chatelier’s Principle

Examples of Dynamic Equilibrium

  1. The carbon cycle
  2. The oxygen cycle
  3. The nitrogen cycle
  4. The water cycle
  5. The phosphorus cycle

A few examples of dynamic equilibrium in our everyday life are listed below:

When a bottle of an aerated drink is opened and half of the drink is poured out, the liquid carbon dioxide is slowly converted into gaseous carbon dioxide until a new point of equilibrium is reached. At this point, the rate of conversion of CO2 from gas to liquid is equal to the rate of conversion of CO2 from liquid to the gaseous phase.

The single-phase system in which acetic acid undergoes dissociation, leading to an acid-base equilibrium, can be described by the following reaction:

CH3COOH ⇌ CH3COO– + H+

In the gaseous phase, the dimerization of nitrogen dioxide can be observed. Reaction: 2NO2 ⇌ N2O4

Henry’s Law (link) is applicable in the first example of dynamic equilibrium provided above, wherein the equilibrium concentration of carbon dioxide in the liquid phase is proportional to the partial pressure of the CO2 gas in the bottle.

Reaction: N2 (g) + 3H2 (g) ⇌ 2NH3 (g)
Industrial Synthesis of Ammonia via Haber’s Process: N2 (g) + 3H2 (g) ⇌ 2NH3 (g)

Difference Between Static and Dynamic Equilibrium

Static equilibrium is when an object’s velocity and acceleration are both zero, while dynamic equilibrium is when the net force acting on an object is zero, but its velocity and acceleration may not be zero.

Static equilibrium refers to a condition where the reaction occurring in a system is completely halted and there is no movement between the reactants and the products associated with the chemical reaction.

If the forces acting on an object are equal and opposite, and the object’s content and composition remain unchanged, then no movement of the object occurs. This is known as static equilibrium.

The key differences between static and dynamic equilibrium are outlined in the table below.

| Static vs Dynamic Equilibrium |

Dynamic Equilibrium Static Equilibrium
State of balance in a system that is changing State of balance in a system that is not changing

| This type of equilibrium is irreversible in nature. |

| This equilibrium implies that the reactants and the products are in a state of balance, with no further chemical reaction occurring in the system. |

| In dynamic equilibrium, the forward and the backward reaction rates are equal | In static equilibrium, the forward and backward reaction rates are equal to zero |

| It can occur in both open and closed systems | It can only occur in closed systems |

However, the resultant force acting on both of these types of equilibria in a system is zero, and thus, generally, neither of these types of equilibrium display any visible changes.

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Ionic Equilibrium

Physical Equilibrium

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