Rate equations

• What does the rate of a reaction indicate?

  It shows how fast reactants are converted into products.

  
• What factors does the rate of a reaction depend on?

  It depends on the concentrations of the reactants and a rate constant.
• What do the constants m and n represent in a rate equation?

  They show the order of the reaction with respect to that species.

  
• How is the total order of a reaction determined?

  It is found as the sum of the separate orders of the reactants.
• What are the different orders of reaction and their effects?

  • **Zero Order**: No impact on rate; Rate = k
  • **First Order**: Directly proportional; Doubling concentration doubles the rate; Rate = k[A]
  • **Second Order**: Proportional to concentration squared; Doubling concentration increases rate by four; Rate = k[A]²

  
• What is the rate constant (k) in a reaction?

  It is constant when the reaction temperature is constant.
• How can the rate constant (k) be found?

  By rearranging the rate equation for that reaction.
• What affects the units of the rate constant (k)?

  They vary depending on the number of species and their orders of reaction.
• What does the Arrhenius Equation show?

  It shows how the rate constant k and temperature are related exponentially.

  
• How can the logged form of the Arrhenius Equation be represented graphically?

  As 'y = mx + c' with lnk against 1/T, where the gradient is negative and constant.

  
• What is the y-intercept in the Arrhenius Equation graph?

  It is lnA.

  
• What determines the overall rate of a reaction?

  The overall rate is determined by the slowest step of the reaction.

  
• How can the rate determining step be identified?

  By looking at which steps include the species in the rate equation.

  
• In a reaction sequence, how can you determine which step is the rate determining step?

  Identify the step where all reactants are included in the rate equation.

  
• How can rate equations be determined experimentally?

  By monitoring the concentration of a reaction mixture over time.
• What is the purpose of drawing a tangent to the concentration-time graph?

  To find the rate at the exact concentration known at t=0.

  
• What is done after obtaining the rate from the concentration-time graph?

  The method is repeated at varying concentrations to gather data.
• What can be plotted to determine the order of reaction?

  A graph of rate against concentration can be plotted.