Understanding the Effect of Temperature on Reversible Reactions at Equilibrium

Introduction

• Focus on the effect of temperature on reversible reactions at equilibrium
• Content is aimed at higher-tier students
• Important to potentially review multiple times for comprehension

Recap of Le Chatelier's Principle

• States that if a system at equilibrium experiences a change in conditions, it will adjust to counteract the change
• Previous discussion: effect of changing concentration

Effect of Temperature on Reversible Reactions

• Example reaction: NO2 forming N2O4 (reversible)
• Key Point: Forward reaction is exothermic
  • Exothermic: energy release leads to an increase in system temperature
  • In reversible reactions, if one direction is exothermic, the other is endothermic
  • Reverse reaction (endothermic): energy absorbed, system temperature decreases
• Every reversible reaction varies; exam questions will provide necessary details

Effect of Increasing Temperature

• Increasing temperature leads to a shift in equilibrium to counteract the change
• Equilibrium shifts to the left:
  • Reduces temperature by favoring the endothermic reverse reaction
  • Result: Increase in NO2, decrease in N2O4

Effect of Decreasing Temperature

• Decreasing temperature also causes equilibrium to adjust
• Equilibrium shifts to the right:
  • Increases temperature by favoring the exothermic forward reaction
  • Result: Increase in N2O4, decrease in NO2

Exam Preparation Tips

• Practice with questions on temperature effects in a revision workbook
• Workbook available via an online link

Conclusion

• Aim: Understand and describe the effect of temperature change on reversible reactions at equilibrium