If the initial rate of H2 to disappear is 2.0 moles per second, what is the rate of appearance of NH3 at the same time? N2(g) 3 H2(g) ⇌ 2 NH3(g)

1.33 moles per second

Explanation:

From the balanced equation of reaction, 3 moles of H2(g) need to disappear/be consumed before 2 moles of NH3(g) can be formed/appear.

According to reaction law, the rate of disappearance of reactants is equal to the rate of appearance of products.

Now, only 2 moles per seconds of H2 has disappeared initially;

3 moles H2 is needed for 2 moles NH3

2 moles H2 will give;        2 x 2/3 = 4/3 or 1.33 moles

Hence, if the initial rate of disappearance of H2 is 2.0 moles per second, the initial rate of appearance of NH3 would be 1.33 moles per second.