AS Chemistry Kinetics

Card Set Information

AS Chemistry Kinetics
2016-01-16 19:33:43
AS Chemistry Unit 2
AS Chemistry Unit 2
Show Answers:

  1. What factors affect the rate of reaction? (5 marks)
    • Concentration
    • Temperture
    • Catalyst
    • Pressure
    • Surface area
  2. Collision theory states...( 2 marks)
    • Particles must collide with a certain amount of Kinetic energy
    • Particles must collide in a certain orientation
  3. How does temperature increase the rate of reaction?  (4 marks)
    • As temperature increase the average kinetic energy of each particle increases.
    • This results in particles moving faster.
    • This means more collisions will have sufficient energy to result in a reaction
    • And so the reaction will be faster
  4. How does Surface area increase the rate of reaction?
    Increasing surface area will cause collisions to occur more frequently between the reactant particles and this increases the rate of the reaction.
  5. How does the Maxwell- Boltzman distribution show the effects of temperature? (3 marks)
    • As the temperature increases, the graph shows that a significantly bigger proportion of particles have energy greater than the activation energy, so the frequency of successful collisions
    • increases

    The graph spreads out

    The peak and the mean move right
  6. Which reaction is better, homogeneous reaction or heterogeneous reaction and why?
    Homogeneous, because particle can intermingle freely, increasing opportunity for reaction to take place.
  7. How do increase the rate of reaction in heterogeneous reaction?
    Increase the surface area of the reactants
  8. How do catalyst increase the rate of reaction?
    Catalyst lower the activation energy required for a successful collision to take place
  9. How does the Maxwell- Boltzman distribution show the effects of a catalyst? ( 2 marks)
    The activation energy line moves left

    Greater proportion of particles possess enough KE to conduct successful collisions
  10. What apparatus do you use to measure rate of reaction? ( 2marks)
    • Measure how much water displaced from the gas
    • Measure the volume of gas produces
  11. Why do you measure the initial rate of reaction and how do you do it? ( 2 marks)
    It the most accurate measurement in order to compare it with other reaction

    You draw a tangent at the start of the reaction
  12. What other ways are there to measure the rate of reaction? ( 5 marks)
    • Measuring the changing mass of a reaction mixture by seeing the rate of mass decrease
    • Monitor colour change (Hydrogen peroxide and sulfuric acid example)
    • Titrimetric analysis 
    • Colormetric analysis
    • Conductimetric analysis
  13. How does titrimetric analysis work? (3 marks)
    • Removing small portions of the reaction mixture (aliquots) at regular intervals
    • Aliquots added to another reagent which stops( quenches) the reaction
    • Quenched aliquots can be titrated to find concentration of a known compound
  14. How does Colorimetric analysis work?
    Colour changed observed using a photoelectric colorimeter
  15. How does Conductimetric analysis work?
    Measuring the conductivity changes in the mixture over time as they reflect the number of ions present.
  16. What happens during a reaction? ( 3 marks)
    • When particles collide with the correct orientation, they slow down and KE is turnt into potential energy
    • If there combined KE is less than the activation energy , they fall down the activation hill gaining there original KE back
    • If combined KE is more than the activation energy, they form  product, overcoming the hill
  17. What is reaction profile
    It shows the relationship between activation energy and potential energy
  18. What  happens during a reaction? ( 3 marks)
    • When particles collide with the right orientation their KE is converted into potential energy and speed slows.
    • If their combined KE is less that the activation energy, they return to the reactant with original KE
    • If combined KE is more than activation energy, they form a new product.