Question

Explain the difference between physical equilibrium and chemical equilibrium. Give two examples of each.

Short answer

Physical equilibrium involves a balance of physical processes, like melting or evaporation, with no chemical reactions. Chemical equilibrium, on the other hand, involves a balance of forward and backward chemical reactions. Examples of physical equilibrium include the melting and freezing of ice at a consistent temperature, and the evaporation and condensation of water in a closed container. Examples of chemical equilibrium include the Haber Process for producing ammonia, and the formation and decomposition of hydrogen iodide.

Step-by-step solution

Define Physical Equilibrium

Physical equilibrium refers to the state where the physical processes (like melting, boiling, evaporation etc.) in the system are occurring at the same rate forward and backward. In physical equilibrium, no chemical reaction happens; it is only the physical state changes. Some of the system's properties, such as pressure, volume or temperature, may exhibit steady-state behavior.

Examples of Physical Equilibrium

1. When ice melts, it becomes liquid water. In a closed system at a stable temperature, the rate of ice melting will be equal to the rate of water freezing, maintaining equilibrium.\n2. In a closed container partially filled with water, the rate of evaporation of water will be equal to the rate of condensation of the water vapor. This is another example of physical equilibrium.

Define Chemical Equilibrium

Chemical equilibrium is the state in which both reactants and products are present in concentrations which have no further tendency to change with time. It typically involves visible chemical changes, such as the decomposition of a chemical compound in a reaction. Even though the concentration of the substances doesn't change over time in chemical equilibrium, the chemical reaction still proceeds but at an equal rate in both directions (forward and reverse).

Examples of Chemical Equilibrium

1. The Haber Process for the production of Ammonia is an example. In this process, Nitrogen and Hydrogen react to form Ammonia gas. The reaction proceeds equally in both directions - formation and decomposition of Ammonia, achieving a chemical equilibrium.\n2. The reaction between Hydrogen and Iodide ions to form Hydrogen iodide is another example. Here too, the forward and backward reactions proceed at an equal rate, achieving chemical equilibrium.