## Chemistry: The Central Science (13th Edition)

For the reaction: aA +bB cC + dD the expression for K would be K = $\frac {[C]^c[D]^d} {[A]^a[B]^b}$ If the equilibrium constant had a value of 0, it would imply that the concentration of (one of) the products is equal to 0. This would mean that the reaction does not proceed as written. When an equation is drawn with a single-headed arrow, it means that the reaction proceeds almost to completion, and therefore the concentration of the products is very large and the concentration of the reactants is small. This would make K a very large number.