Chemical equilibrium are essential for oxygen transport and delivery from the lungs to muscles, and are influenced by CO molecules and hemoglobin. When a liquid evaporates, molecules with higher kinetic energy escape into the vapour phase, while others remain in the liquid phase. Equilibrium results in constant vapour pressure, with the number of molecules leaving the liquid equaling the number returning. The equilibrium mixture consists of reactants and products, and can be established for both physical processes and chemical reactions.

Reactants in a closed vessel react to give products, with reactant concentrations decreasing and products increasing. The speed of reaction depends on experimental conditions and reactant nature. In a closed vessel at a specific temperature, reactants decrease and products increase. The stage of dynamic equilibrium is where forward and reverse reactions are equal, and no change in the concentrations of various species in the reaction mixture occurs.

There are three groups of reactions: nearing completion, reactions with small product amounts, and reactions with comparable reactant and product concentrations. The extent of a reaction in equilibrium varies with experimental conditions, and optimizing operational conditions is crucial for favorable equilibrium in industry and laboratories. Ice and water in an insulated thermos flask at 273K and atmospheric pressure are in equilibrium. The mass of ice and water remains constant when the temperature remains constant, and the equilibrium state is not static. The rate of evaporation and condensation is equal at atmospheric pressure and 273K. The normal melting or freezing point of a pure substance at atmospheric pressure is the temperature where the solid and liquid phases are at equilibrium.

The number of water molecules from the gaseous state into the liquid state increases until equilibrium is reached. The equilibrium vapour pressure of water is the pressure exerted by water molecules at a specific temperature when they are in equilibrium. The time taken for complete evaporation depends on the nature of the liquid, the amount of the liquid, and the temperature.

Water and water vapor are in equilibrium position at atmospheric pressure (1.013 bar) and at 100°C in a closed vessel. The boiling point of water is 100°C at 1.013 bar pressure, and the boiling point depends on atmospheric pressure and altitude. At high altitudes, the boiling point decreases.

In a closed vessel, solid iodine sublimes to give iodine vapour, while iodine vapour condenses to give solid iodine.

Equilibrium involving dissolution of salt or gas in solution

 

Physical equilibrium refers to the dissolution of solids or gases in liquids, with a saturated solution occurring when no more solute can be dissolved at a given temperature. This equilibrium is dynamic and depends on temperature, with the rate of dissolution equal to the rate of crystallization. The equilibrium is established between gaseous molecules and liquid molecules under pressure, as per Henry's law.

The solubility of a gas in a solvent is proportional to the pressure of the gas above the solvent. The amount of gas dissolved in the liquid decreases with temperature. The soda water bottle is sealed under high solubility in water, and when opened, some of the dissolved carbon dioxide gas escapes to reach a new equilibrium condition.

Solubility for solids in liquids remains constant at a given temperature, while the concentration of a gas in liquid is proportional to the pressure of the gas over the liquid. Equilibrium is possible only in a closed system at a given temperature, with both opposing processes occurring at the same rate and maintaining a dynamic but stable condition.