Consider this equilibrium: I2(s) + H2O(l) ⇌ H+(aq) + I-(aq) + HOI(aq). What is the Keq expression for this equilibrium?
The expression is
We often consider a generic reaction of the form
aA +bB ⇌ cC +dD
The equilibrium constant expression for this reaction is
Notice that it is always "products" over "reactants". Each component A, B, C, and D is raised to the power of its coefficient a, b, c, and d in the balanced equation.
The concentration of a solid or of a liquid does not change during a reaction. We omit it from the equilibrium constant expression.
Consider the equation
I₂(s) + H₂O(l) ⇌ H⁺(aq) + I⁻(aq) + HOI(aq)
I₂ is a solid, and H₂O is a liquid. Their concentrations do not change during the reaction. We omit them from the
All the products are in solution. They can change their concentrations. We keep them in the