Effect of Concentration and Pressure on Rate of Chemical Reaction

Introduction

• Objective: Describe and explain the effect of the concentration of reactants or the pressure of reactant gases on the rate of a chemical reaction.
• Key Concept: Collision Theory
  • Reactions occur when particles collide with sufficient energy.
  • Rate determined by frequency of successful collisions per second.

Collision Theory Recap

• Initial Phase: Rapid reactions due to a large number of reactant molecules leading to frequent collisions.
• Over Time: Reaction slows as reactant molecules deplete, reducing collisions.
• End of Reaction: Stops when reactant molecules are exhausted, thus zero collisions.

Effect of Concentration on Reaction Rate

• Experiment Setup: Two containers with reactant particles (dissolved in water).
  • Both containers have identical volumes.
• Key Observation:
  • Right-hand container has double the particle concentration compared to the left.
  • Higher concentration leads to more collisions per second.
  • Reaction rate in the right-hand container is twice that of the left.
• Conclusion: Rate of reaction is proportional to concentration.

Effect of Pressure on Reaction Rate in Gases

• Principle: Same as with concentration in solutions.
  • Higher gas pressure = Higher number of collisions per second.

Graphical Representation

• Reaction Product Plots:
  • Higher concentration results in:
    • Faster reaction (steeper line on graph).
    • More product formation due to more initial reactants.

Upcoming Content

• Next Video: Required practical focusing on concentration effects on reaction rates.
• Resources: Vision workbook contains additional questions on this topic.

Conclusion

• Outcome: Ability to describe and explain the impact of reactant concentration or gas pressure on chemical reaction rates.