Kinetics Review Chem 12 1996
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1. Define the following:
Activation energy, Mechanism, Activated Complex, Successful collision, Catalyst, Reaction rate, Enthalpy, Intermediate, Homogeneous reaction, Rate determining step, Heterogenous reaction.
2. Na2CO3(aq) + 2HCl(aq) ------> CO2(g) + 2NaCl(aq) +H2O(l)
a) Give four ways to increase the rate of the reaction.
b) Give three properties that you could measure in order to determine the rate of the rection. For each one describe how they would change during the experiment.
3. Zn(s) + 2HCl(aq) ----> H2(g) + ZnCl2(aq)
a) Give five specific ways to increase the rate.
4. In low light, H2 and Cl2 do not react at all. When exposed to UV light, they react explosively! Explain using the collision theory.
5. A mixture of KClO3 and C12H12O11 do not react at all at room temperature. A drop of H2SO4 starts the reaction, slowly at first, then it quickens into a flaming inferno. Explain using the collision theory.
6. Water puts out a fire. Explain using the collision theory.
7. A glowing splint reignites in pure O2. Explain using the collision theory.
8. Enzymes in the human body allow the oxidation of carbohydrates at 37 degrees celcius.
9. Draw an exothermic PE diagram. Include a catalyst. Label the change in enthalpy, the forward and reverse activation energies and the activated complex.
10. Repeat the above for an endothermic reaction.
12. A + WY -------> AWY FAST
AWY + HA -------> A2WY + H SLOW
A2WY + HA -------> A3 + WY + H FAST
I. List the following:
a) the overall equation
b) a catalyst
c) Intermediates
d) Reactants
e) Products
II. Describe how each change affects the rate.
a) increasing the concentration of A
b) increasing the concentration of H
c) increasing the concentration of HA
d) removing WY completely
e) Decreasing the temperature
13. Describe the KE and PE changes as two molecules:
a) approach to collide,
b) form an activated complex, and
c) form products in an exothermic reaction.
14. Draw the PE diagram for a mechanism with three steps. How many activated complexes are there? How many intermediates are there?
15. Describe as endo or exothermic.
a) 2H2 + O2 ------> 2H2O + 300kJ
b) NH4NO3(s) -------> NH4NO3(aq) ?H = +150kJ
16. Change each equation in 15. from standard to ?H notation or vice-versa.
17. Which reaction at room temperature is faster and why?
a) Pb+2 + 2Cl-1 ------> PbCl2 or
b) 2H2 + O2 ------> 2H2O
18. List three comercial catalysts (they are in your textbook on page 504 under Do you know?).
19. Calculate the rate in mole
s/s.
|
Moles H2 |
10.0 |
15.0 |
21.0 |
24.0 |
|
Time (seconds) |
200 |
300 |
400 |
500 |
20. Indicate how each change will effect the rate of the reaction and the PE diagram and explain with the collision theory.
a) increasing the temperature
b) increasing the concentration of a reactant
c) increasing the concentration of a product
b) addition of a catalyst
21. X + Y ------> XY slow
XY + Z ------> XYZ fast
XYZ + W ------> XYW + Z fast
a) Identify intermediates, the catalyst and the rate determining step.
b) If the concentration of X was increased will the rate increase?
22. You can only increase the surface area of a substance if it is in certain physical state. What is it?
23. Two solid reactants react. Is it a homogeneous or heterogeneous reaction?
24. What is the mathematical relationship between reaction rate and activation energy; reaction rate and reactant concentration; reaction rate and temperature?
25. Draw a collision energy distribution diagram for a reaction where the y axis is fraction of collisions and the x axis is collision energy. Draw the Ea line showing about 10% of the collisions having sufficient energy. Draw the Ea line for the catalyzed reaction where 20% have sufficient energy.
26. Which reaction would likely be faster? Explain.
a) 2Al (s) + 3I(s) -------> 2AlI3(s)
b) 2OCl- (aq) + 2H+ (aq) -------> Cl2 (g) + 2OH- (aq)