Question

If A Reaction has Large Value Of Kc,will It Go To Completion And Why?

Answer 1

Answer on Question #41751 - Chemistry - Other

Question

If a reaction has large value of $K_{C}$, will it go to completion and why?

Answer

Let us consider a chemical reaction in general form:

$$aA + bB \rightarrow cC + dD,$$

where A and B are reactants, C and D are products and a, b, c and d are stoichiometric coefficients.

The expression of $K_{C}$ for the reaction:

$$K_{C} = \frac{[C]^{c}[D]^{d}}{[A]^{a}[B]^{b}},$$

where $[A]$, $[B]$, $[C]$ and $[D]$ molarity of reactants and products at the equilibrium.

An equilibrium reaction proceeds until reaching equilibrium. And the value of $K_{C}$ characterizes this equilibrium. Since the products are in the numerator of $K_{C}$ expression, the greater the $K_{C}$ the greater the concentration of products at the equilibrium, and vice versa: the small value of $K_{C}$ indicates great amount of reactants and small amount of products at the equilibrium.

So, if a reaction has large value of $K_{C}$, amount of products considerably exceeds the amount of reactants, and this means the reaction reaches close to completion.

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