How Fast

• What does it mean when a reaction is at equilibrium?


  The rate of forward and reverse reactions are equal
• What are the methods that can be used to measure equilibrium?


  • Measure change in colour or colour intensity using colorimeter
  • Use pH probe
  • Measure electrical conductivity
  • Titration (when equilibrium is slow)
• What does mole fraction mean?


  The amount of a given component in a given reaction mixture
• What is the equation used to calculate mole fraction?


  Mole fraction = number of moles of substance A / total number of moles of all substances
• What does partial pressure mean?


  The pressure exerted by a single species in a reaction vessel
• What is the symbol for partial pressure?


  P
• What is the equation used to calculate partial pressure?

  Partial pressure = mole fraction x total pressure
• What is the relationship between concentration of a substance and its partial pressure?


  Concentration of a substance is proportional to its partial pressure
• What are the 3 common units of pressure used in chemistry?

  • Pascals
  • Atmospheres
  • Newtons per square metre
• What type of brackets are used in Kc expressions?


  Square brackets
• What type of brackets are used in Kp expressions?


  Round brackets
• How do you calculate the units for Kp?


  Write out the units for the partial pressures in the same arrangement as the Kp equation and cancel out/multiply together
• What is the symbol of the equilibrium constant?


  K
• What does it mean when K is greater than 1?


  Reaction favours products
• What does it mean when K is less than 1?


  The reaction favours reactants
• What is the effect of increasing temperature on K?


  Equilibrium shifts to the direction of the endothermic reaction
• What is the effect of decreasing temperature on K?


  Equilibrium shifts to the direction of the exothermic reaction
• What is the only factor that affects K?

  Temperature
• What is the effect of increasing temperature on K for a forward endothermic reaction?


  K increases as temperature increases
• What is the effect of increasing temperature on K for a forward exothermic reaction?


  K decreases as temperature increases
• What effect does a catalyst have on K?


  Catalysts do not affect the position of equilibrium; they only affect the rate of reaction