How does the length of time it takes for a reaction to occur relate to the rate of the reaction?
Longer time would mean a slower rate of reaction.
For example, in the Haber Process, the formation of ammonia would be favoured by a low temperature and high pressure. However, at low temperatures, the reaction rate would be too slow i.e. reaction would occur over a longer period of time for it to be practical.
Hope this helps :/