Question

Write the equilibrium constant expression for the decomposition of baking soda. Deduce the unit of K_c from the above expression.

Answer 1

The expression for equilibrium constant does not contain the concentration of pure solids.

[Note: Considering gaseous reactants and products, in this reaction, Δn = 2 – 0 = 2

∴ Units of K_c = (mol dm^-3)^Δn

= (mol dm^-3)²

= mol² dm^-6 

Thus, the units of the above reaction is mol² dm^-6 .]