Collisions of particles that have the minimum energy to react.
The collisions must be of sufficient energy to react.
The minimum amount of energy needed to bring about a reaction.
They are lowered.
It remains unchanged.
Two opposing reactions that occur at equal rates.
The reaction may be ``shifted'' when stresses are applied to the system.
2 H2 + N2 2 NH3
Ammonia is an important starting material in the manufacture of fertilizers and explosives.
The temperature was kept relatively low, the pressure was kept high, and the ammonia was removed as it was produced.