# Reaction rates | Chemical Kinetics: Rate Laws

Here is a reaction: N2(g) + 3 H2(g) → 2 NH3(g).

If the rate of formation of ammonia is 0.272 M.s-1, what is the rate of disappearance of H2?

rate of the reaction = -   =

rate of formation of NH3 =  $\frac{∆\left[{\mathrm{NH}}_{3}\right]}{∆\mathrm{t}}$

rate of disappearance of H2 = - $\frac{∆\left[{\mathrm{H}}_{2}\right]}{∆\mathrm{t}}$

⇒ rate of disappearance of H2$\frac{3}{2}$ x rate of formation of NH3

⇒ rate of disappearance of H2 =  x 0.272 = 0.408 M.s-1