Question

why is it important to know the rate of a reaction

Answer 1

Reaction rates are the reason why some reactions happen, while others do not.

Equilibria are one very important application of reaction rates. Some reactions are reversible, which means they can happen both ways. These reactions are said to be in "equilibrium". The ratio of reactants to products in the reaction vessel is determined by the difference between the forward and reverse reaction rates. A higher forward reaction rate will yield more products, and a higher reverse reaction rate will yield more reactants. The system is kept in a dynamic equilibrium, which means that both forward and reverse reactions are happening simultaneously.

Changing conditions such as temperature, pressure or reactant concentration can alter the forward and reverse reaction rates. One known example of this is in ammonia production, where the reaction is carried out at very high pressure to maximise the rate of the forward reaction, which yields a desirable product (ammonia).

Having a slow rate of reaction means that more time is spend on manufacturing the product, whereas having a fast rate of reaction, there is less time spent on manufacturing the product. Manufacturers are always aiming to make a profit so they increase the rate of the chemical reaction which leads to spending less money and time.