Why is the rate of reaction important in industry?

1 Answer
Jun 10, 2018

Answer:

Chemical industries aim to create high rates of reactions, as this means their desired product will be produced faster, meaning they can make more money. However, they often have to make compromises when dealing with reversible reactions.

Explanation:

Rate of reaction is the time taken for a reaction to complete. The ultimate goal of any industry is to make as much money as possible, so industries are keen to try and have as fast a rate as possible.

High rates of reaction are achieved by increasing the concentration/pressure of the reaction mixture. This works because for a reaction to occur, particles of the reactants must collide with each other. Not only must they collide, but they must have enough energy to overcome the activation energy of the reaction, AND they must be correctly orientated (in other words, if the reacting bit of one molecule is facing the wrong way during a collision the reaction won't occur).

Hence, increasing the temperature gives the particles more energy, meaning more particles will have enough energy to overcome the activation energy; and increasing the concentration/pressure means the particles are closer together, so will collide more often. Both of these factors increase the frequency of successful collisions, and hence increases the rate of reaction.

When a reaction is irreversible, this process is straightforward. However, when dealing with a reversible reaction, the manufacturer must also take in to account:

1) Whether the forward reaction is exothermic or endothermic. When the temperature of an equilibrium system is changed, the equilibrium shifts to oppose the change (read up on Le Chatalier's principle if this is unfamiliar). Eg. when the forward reaction is exothermic, increasing temperature will decrease the yield of products
2) When dealing with gases, whether there are fewer or more moles of gas in the products. When the pressure of a gaseous equilibrium system is increased, the yield of the side with the fewest moles will increase (this is again due to Le Chatalier's principle)

As a result, there will be some situations in which increasing the temperature and pressure will increase the rate of reaction, but decrease the overall yield of product (ie. you make your product quicker, but you make less of it). So manufacturers are interested in rates of reaction because they are interested in producing the highest yield of desired product as possible.