Equilibrium Test - 2

At equilibrium, the rate of evaporation is equal to the rate of condensation.

It may be represented by H₂O (l) ⇌ H₂O (vap)

The double half arrows indicate that the processes in both the directions are going on simultaneously. The mixture of reactants and products in the equilibrium state is called an equilibrium mixture

there is no change in the conc of reactant and product. At dynamic equilibrium, reactants are converted to products and products are converted to reactants at an equal and constant rate.  Reactions do not necessarily—and most often do not—end up with equal concentrations. Equilibrium is the state of equal, opposite rates, not equal concentrations.

Ice and water kept in a perfectly insulated thermos flask at 273K and the atmospheric pressure are in equilibrium state and the system shows interesting characteristic features. The mass of ice and water do not change with time and the temperature remains constant. However, the equilibrium is not static. The intense activity can be noticed at the boundary between ice and water. Molecules from the liquid water collide against ice and adhere to it and some molecules of ice escape into liquid phase. There is no change of mass of ice and water, as the rates of transfer of molecules from ice into water and of reverse transfer from water into ice are equal at atmosphere pressure and 273K.

 The number of water molecules from the gaseous state into the liquid state also increases till the equilibrium is attained i.e., rate of evaporation = rate of condensation 

At equilibrium the pressure exerted by the water molecules at a given temperature remains constant and is called the equilibrium.

The number of water molecules from the gaseous state into the liquid state also increases till the equilibrium is attained.

i.e.rate of evaporation = rate of condensation
H₂O(l) ⇌  H₂O (vap)

At equilibrium the pressure exerted by the water molecules at a given temperature remains constant and is called the equilibrium vapour pressure of water increases with temperature.

we place solid iodine in a closed vessel, after sometime the vessel gets filled up with violet vapour and the intensity of colour increases with time. After certain time the intensity of colour becomes constant and at this stage equilibrium is attained. Hence solid iodine sublimes to give iodine vapour and the iodine vapour condenses to give solid iodine. The equilibrium can be represented as,    I2 (solid) ⇌ I2 (vapour)

Water and water vapour 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. For any pure liquid at one atmospheric pressure (1.013 bar), the temperature at which the liquid and vapours are at equilibrium is called normal boiling point of the liquid. Boiling point of the liquid depends on the atmospheric pressure.

This equilibrium is governed by Henry’s law, which states that the mass of a gas dissolved in a given mass of a solvent at any temperature is proportional to the pressure of the gas above the solvent. This amount decreases with increase of temperature.

Soda water, like other carbonated beverages, contains carbon dioxide that has dissolved under pressure. When the pressure is released by opening the soda container, the liquid cannot hold as much carbon dioxide, so the excess bubbles out of the solution. If the soda is left open, additional carbon dioxide will slowly escape into the air. Under warm conditions, the carbon dioxide leaves the solution faster.

Use of isotope (deuterium) in the formation of ammonia clearly indicates that chemical reactions reach a state of dynamic equilibrium in which the rates of forward and reverse reactions are equal and there is no net change in composition.