How can a reversible reaction be forced to go to completion?

A reversible reaction can be forced to go to completion by altering the conditions in such a way that the equilibrium position is shifted entirely toward the products. This can be achieved through several strategies:

  1. Remove Products as They Form: One of the most effective ways to push a reversible reaction toward completion is to continuously remove the products from the system as they are formed. This prevents the concentration of products from building up, which would otherwise shift the equilibrium back toward the reactants. For example, in the synthesis of ammonia, the ammonia gas can be removed as it forms, ensuring that the system is always “pushed” toward producing more ammonia.

  2. Increase the Concentration of Reactants: By increasing the concentration of the reactants, you increase the likelihood of collisions between the reactant molecules, which can shift the equilibrium toward the product side. This helps drive the reaction toward completion, especially if the system can no longer “counteract” the change by reversing the reaction.

  3. Adjust Temperature and Pressure: Changing the temperature or pressure can also shift the equilibrium in favor of the products. For example, in an exothermic reaction, increasing the temperature will shift the equilibrium toward the reactants. To drive the reaction to completion, conditions such as lower temperatures or higher pressures (for gaseous reactions) may be required to favor the products.

  4. Use a Catalyst: While a catalyst does not affect the position of equilibrium, it can speed up the rate at which equilibrium is reached. In cases where the reaction is slow, a catalyst can increase the speed of the forward reaction, helping to reach a point where the reaction appears to go to completion more quickly.

  5. Alter Reaction Conditions (e.g., Solvent or pH Changes): For some reactions, altering the solvent or changing the pH can push the equilibrium in the desired direction. For example, adding a solvent in which the product is more soluble can drive a solid product to dissolve, shifting the equilibrium toward product formation.

Related Questions:

  1. How can you drive the reversible reaction at equilibrium?
  2. How can you increase the maximum yield of a reversible reaction?
  3. How can you drive a reversible reaction to completion?
  4. Do the phase changes in water (solid to liquid, liquid to vapor) represent reversible equilibrium?
  5. How can you decrease the time to attain equilibrium?
  6. How does a change in temperature affect the reaction at equilibrium?
  7. Why are some reactions irreversible while others are reversible?
  8. How do you know if a reaction is reversible or irreversible?
  9. Explain how the rates of forward and backward reactions change when the system approaches equilibrium.
  10. Study the effect of heat on hydrated copper sulfate. Why does this salt look colored, and why does it lose color upon heating?
  11. Can you make an irreversible reaction reversible?
  12. What is the effect of pressure on equilibrium?
  13. Investigate why some reactions are irreversible.
  14. What are the conditions required to shift equilibrium in the forward direction?
  15. How do you determine the position of equilibrium?
  16. Why does pressure affect gaseous equilibria?
  17. Why are combustion reactions generally irreversible?
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