Are solids and liquids included in equilibrium constant?

Equilibrium constant are actually defined using activities, not concentrations. So, pure liquids and solids actually are involved, but since their activities are equal to 1, they don’t change the equilibrium constant and so are often left out.

Why is the molar concentration of solids and liquids constant?

That is because the density of liquids and solids is temperature and pressure dependent. The reason that the molar concentration is often called constant is twofold: the density of liquids and solids has a much weaker dependence on the temperature than gases do therefore it can be regarded as approximately constant.

Why is equilibrium constant not affected by concentration?

Equilibrium constants are not changed if you change the concentrations of things present in the equilibrium. The only thing that changes an equilibrium constant is a change of temperature. The position of equilibrium is changed if you change the concentration of something present in the mixture.

Why is pure liquid and solid concentration taken as unity in equilibrium reaction?

for solids and liquids, volume is also constant as they are incompressible. So concentration is constant and is taken to be unity. For solids or liquids, as mass decreases the volume also decreases by a proportional amount.

Do solids have a concentration?

Excluding extreme changes in pressure and temperature, solids will always have the same concentration. In your example, for a given temperature, the partial pressures and concentrations of the products will not depend on the amount of ammonium chloride present.

Why is there not a constant molar volume for solids and liquids?

With liquids and solids, volume varies greatly depending on the density of the substance. This is because solid and liquid particles are packed close together with very little space in between the particles. However, gases are largely composed of empty space between the actual gas particles (see Figure below).

Why do solids have a concentration of 1?

Because the standard state of solids and liquids is their molar density at room temperature and pressure, which is equal to their “concentrations” anyway. So, a≈1 for pure solids and liquids sufficiently close to 25∘C and #”1 bar”.

Why is the activity of solids and liquids 1?