Answer
Yes, the balanced chemical equation is also necessary.
The value of the equilibrium constant is only useful when you have the equilibrium expression, where you need to the know the reactants and products, and their relative balance coefficients.
For example:
$$K = \frac{[C]^c[D]^d}{[A]^a[B]^b}$$
Which is the equilibrium expression for the reaction:
$$aA + bB \rightleftharpoons cC + dD $$
Work Step by Step
The equilibrium expression is written as:
$$K = \frac{[Products]}{[Reactants]}$$
In order to use this expressions, you need to know who are the products and reactants, and their balance coefficients.
