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The principles of equilibria and reaction rates play a crucial role in the design of conditions for many important industrial processes. 

Ideally, reactants should be converted to products:

(i) as quickly as possible and

(ii) as completely as possible.

The speed of reaction is dependent on the rate of reaction. The percentage yield depends on maximising the amount of product in the equilibrium mixture.

Sometimes conditions can be chosen that produce both a high rate of reaction and a high percentage yield. In other cases, however, conditions that favour a high percentage yield favour a slow rate of reaction or involve high cost. In these situations, optimum conditions are chosen that are a compromise between rate of reaction, yield and cost.

A fast rate of reaction can be produced by using high temperatures. In what kind of reaction would this reduce the yield of products in an equilibrium mixture?

If the reactants to products reaction is exothermic.

In some gaseous equilibrium reactions a higher yield is produced by using high pressure. What additional costs might the use of high pressure incur?

The energy cost in compressing the gases and the cost of using thicker pipes that are able to withstand the higher pressures.

Will a catalyst affect both the rate and yield of an industrial process?

No. A catalyst will increase the rate of reaction but will have no effect on the yield.

Why might a catalyst help make an industrial process more economic to operate?

If a catalyst is used the reaction may take place at a lower temperature and/or pressure and so reduce fuel costs, which are one of the major expenses in a large-scale chemical process.