Question

The Haber reaction for the manufacture of ammonia is:

N₂ + 3H₂ → 2NH₃

Without doing any experiments, which of the following can you say MUST be true?

True False  The reaction is not an elementary reaction.
True False  The reaction is first order in N₂.
True False  Δ[H₂]/Δt will have a positive value.
True False  Reaction rate = -Δ[N₂]/Δt.
True False  Disappearance rate of N₂ = 3 (Disappearance rate of H₂).
True False  Disappearance rate of H₂ = 3 (Disappearance rate of N₂).
True False  The activation energy is positive.

Answer 1

True. The reaction is an elementary process since it is a single step reaction.

True. The reaction is first order in N2 as it is an elementary reaction and in an elementary reaction stoichiometric    coeficient is equal to order.

False. Being on the reactant side [H2] will decrease with time, hence Δ[H2]/Δt is negative.

True. N2 being on the reactant side and with stoichiometric coefficient 1 gives a rate expression as mentioned in the    question.

False. Disappearance rate of N2 = 1/3(disappearance rate of H2)

True. Disappearance rate of H2 = 3(disappearance rate of N2)

True. Although it is an exothermic reaction, it has high activation energy, needing catalysts to start the reaction.

Note: THE REACTION RATE = Disapperance rete of reactant/stoichiometric coefficient= Appearance rate of product/ Stoichiometric coeeficient