Getting the Most from Reactants

Overview of Getting the Most from Reactants

  • Industrial and agricultural processes strive to get the maximum yield from reactants.
  • The loss of reactants or the creation of unwanted products are inefficiencies that reduce profitability.
  • Chemical equilibrium plays a significant role in getting the most out of reactants.

Basic Principles of Yields and Efficiency

  • The theoretical yield is the maximum amount of product that can be made in a chemical reaction based on the quantity of reactants.
  • The actual yield is the quantity of product that is actually made.
  • Percentage yield is calculated using the formula: (Actual yield / Theoretical yield) x 100.
  • Reactions rarely give a 100% yield due to practical issues such as incomplete reactions, side reactions, and losses during purification.

Reversible Reactions and Chemical Equilibrium

  • A reversible reaction is a chemical reaction where products can react together to reform the reactants.
  • In a closed system, these reactions reach a dynamic equilibrium where the rate of the forward and reverse reactions are equal, and the concentrations of reactants and products remain constant.
  • Le Chatelier’s Principle states that if a condition of a reaction at equilibrium is changed, the equilibrium will shift to oppose that change.

Factors Affecting Chemical Equilibrium and Yield

  • Changes in concentration, pressure, and temperature can influence the position of the equilibrium and thus, the yield of product.
  • The effect of a catalyst is to increase the rate of both the forward and reverse reactions equally. It does not affect the position of the equilibrium.

How to Increase Yield in Industrial Processes

  • For a reversible reaction, to obtain a high yield of product, it may be necessary to remove a product from the reaction mixture or to add more of a reactant.
  • Conditions like temperature and pressure are often a compromise between the best possible yield and the fastest rate of reaction.
  • The use of a catalyst can improve the rate of reaction without affecting yield.

Remember, understanding and manipulating the factors influencing chemical equilibrium can improve efficiency and yield in chemical reactions. Always consider not just the chemical reactions, but also the practical and economic factors that can impact yield.