Reversible reactions

• What is a characteristic of reversible reactions?

  They can go backwards.
• What happens to the concentrations of reactants during a reversible reaction?

  Their concentrations fall as they react.
• What occurs to the concentrations of products as they are formed in a reversible reaction?

  Their concentrations increase as they are made.
• What is meant by equilibrium in a reversible reaction?

  Both reactions occur at the same rate.
• What happens to the concentrations of reactants and products at equilibrium?

  They reach a balance and won't change.
• In what type of system is equilibrium reached in reversible reactions?

  In a closed system.
• What does a closed system mean in the context of reversible reactions?

  No reactants or products can escape.
• What is dynamic equilibrium?

  Lots of activity, but no overall effect.
• What factors affect the position of equilibrium in a reversible reaction?

  • Temperature
  • Pressure
  • Concentration of some gases
  • Relative amounts of reactants and products
• What does it mean if the equilibrium lies to the right?

  The concentration of products is greater.
• What does it mean if the equilibrium lies to the left?

  The concentration of reactants is greater.
• How does heating affect the equilibrium of the reaction involving ammonium chloride gas?

  It moves the equilibrium to the right.
• How does cooling affect the equilibrium of the reaction involving ammonium chloride gas?

  It moves the equilibrium to the left.
• What is the relationship between endothermic and exothermic reactions in reversible reactions?

  • Endothermic in one direction
  • Exothermic in the other direction
  • Energy transferred equals energy released
• What happens during the thermal decomposition of hydrated copper sulfate?

  It becomes anhydrous copper sulfate and water.
• What occurs when blue hydrated copper sulfate crystals are heated?

  They lose water and turn white.
• What happens when water is added to anhydrous copper sulfate?

  It turns back into blue hydrated copper sulfate.
• What does "exo" mean in exothermic reactions?

  External or gives out heat.
• What does "endo" mean in endothermic reactions?

  Internal or absorbs heat.
• What is a revision tip for understanding equilibrium positions?

  • More products = equilibrium lies to the right
  • More reactants = equilibrium lies to the left