# Why is the rate law typically written in terms of reactants whilst equilibrium constants are written in terms of products*?

That is, equilibrium constants are written in terms of products/reactants or for Ksp, in terms of products only.

Why doesn't the rate law also focus on products?

I usually see it written in terms of reactants.

• Because products do not influence the rate of a non-equilibrium reaction, while products are the reactants of the reactants in the backward reaction in equilibrium – Greg Apr 26 '17 at 0:32
• If the reaction is $A \rightarrow B$ then you can write $dA/dt=-k_1A$ or $dB/dt=+k_1A$, to solve you also have to know how much A and B are present initially, if in equilibrium $A = B$; $K_e=[B]_e/[A]_e$ – porphyrin Apr 26 '17 at 8:38