Question

What is the ${k_{eq}}$ equation?

Answer 1

${k_{eq}}$ is known as the equilibrium constant. It is a necessary term as it is used in the characterization of any chemical reaction. So, let’s first understand the chemical equilibrium. A chemical equilibrium is a resting state of any reaction.

Complete answer:
Chemical equilibrium can be defined as the state or the resting state in which the concentration of both reactant and product reaches at the stage that there will be no further change in their concentrations with time.
At this equilibrium stage the rate of forward reaction is equal to the rate of backward reaction.
Though, at this equilibrium stage, there is no observable change in the chemical equation, but it does not mean that equation has stopped, rather, the reaction is taking place continuously but the changes are unnoticeable.
And to define this equilibrium state, we need the expressions like:
${k_{eq}}$ i.e. Equilibrium constant in terms of concentration of reactants and the product
Or, ${k_p}$ i.e. Equilibrium constant in terms of pressure of reactants and the product
So, ${k_{eq}}$ is defined as the amount of products raised to the power of their coefficients in a chemical equation divided by the concentration of the reactants raised to the power of their coefficients in a chemical balanced equation.
Let’s suppose a reaction for a better understanding:
The reaction is:
$aA + bB \Leftrightarrow cC + dD$
So the, ${k_{eq}}$ $= \dfrac{{{{\left[ C \right]}^c}{{\left[ D \right]}^d}}}{{{{\left[ A \right]}^a}{{\left[ B \right]}^b}}}$
Hence, the ${k_{eq}}$ equation is clear.

Note:
The equilibrium constant is affected by the change in temperature. Like for an endothermic reaction, an increase in the temperature increases the equilibrium constant. This is because by increasing the temperature of the endothermic reaction, a forward reaction is favoured.