In a catalytic reaction involving the formation of ammonia by Habers process N2+3H2→2NH3, the rate of appearance of NH3 was measured as 2.5×10−4molL−1s−1. The rate of disappearance or H2 will be:
N2(g)+3H2(g)→2NH3(g)
Rate=−d[N2]dt=−d[H2]3dt=+d[NH3]2dt
∴−d[H2]dt=32d[NH3]dt
=32×2.5×10−4molL−1s−1
= 3.75×10−4molL−1s−1