Essential Questions on Energy of Reactions and Reaction Kinetics
I. What are Potential Energy graphs for Chemical reactions?
a. How do Endothermic and Exothermic reactions differ?
b. What is Delta H and where can it be found on the PE graph?
c. What is Ef, Er, Activated Complex?
d. Do bond energies affect placement of reactants and products?
e. What is Reaction Mechanism?
1. What are Net equations and Sub equations?
2. What is a Rate Determining Step?
II. What can we do to increase the rate of a chemical reaction?
a. Increase the Concentration
b. Increase the Temperature
1. More Collisions
2. More Energetic Collisions
c. Increase the Pressure
d. Add a Catalyst
1. New Reaction Mechansim
2. Lower Activated Complex, Ef, Er. Same Delta H
3. Same amount of product
III. How do we find the Delta H of a Chemical Reaction?
a. Write a balanced net equation
b. Find and write the needed sub equations using the Heat of
Reactions and Heat of Combustions Charts.
1. If reversed, change the sign of the Delta H.
2. Multiply as stated by the Net equation and include the
Delta H.
c. Make sure the Subs add up algebraically to the Net equation.
d. Add up the Delta H’s (take care with signs).
IV. How do we draw a PE graph from given data?
a. Determine the given starting point
b. Calculate the mathematical relationship of the six values: Delta
H, Activated Complex, Reactant level, Product level, Ef and Er.
c. This is frequently followed by an expected Dimensional
Analysis calculation.
Rate and Energy of Chemical Reactions Worksheet I
Name _____________________ Per _______
1. Energy or heat of reaction
2. Delta H
3. Activation energy
a. Ef
b. Er
4. Reaction Mechanism
a. sub equations
b. net equation
5. Catalyst
a. New reaction mechanism
b. Lower Activation Energy
c. Products occur faster
d. No additional products
e. Catalyst particle is NOT consumed but reused over and over
6. Inhibitor
7. Endothermic
8. Exothermic
9. Activated Complex
10. Collision Theory
11. Rate Determining step
12. Rate determining factors
a. Concentration (Molarity)
b.Temperature
i. number of collisions
ii.
energy per collision
b. Size of particles
c. Catalyst
Rate and Energy of reaction Worksheet II
Name__________________________ Per _________
Label all parts of these graphs:
1. Draw 2 Potential Energy diagrams, one for a fast and 1 for a slow reaction and indicate why they differ.
2. Draw 2 PE diagrams, one for a reaction that goes nearly 100% toward products and the other that stops
at a point where the reactants and products are of about the same concentration.
3. Draw 2 PE diagrams, one for a slow reaction and then the same reaction with a catalyst added.
4. Draw 2 PE diagrams, one for exothermic reactions the other for endothermic reactions.
5. Write a paragraph explaining what happens and how when a catalyst is added and include comments
about what does not happen, too.
Chemistry
Energy of Reactions Worksheet III
Name___________________ Per. ______
1.
Find the Delta H of Nitrogen monoxide reacting with oxygen to form Dinitrogen tetraoxide. (-171.4)
2.
If 3.5 pounds of Nitrogen monoxide is reacting, find the Kj involved. (4.54e3Kj)
3.
If the Potential Energy level of the Nitrogen monoxide is 1300 Kj. and the Ef is 250 Kj,, find the
Er by drawing a PE graph to scale.
(Er=421.4Kj)
4. a. Calculate the Heat of Formation of Sulfur Trioxide from its elements. Use the following: (-495Kj)
S + O2  SO2
Delta H = -296.8 Kj/mole SO2
SO2 + ½ O2  SO3 Delta H = -198.2 Kj/mole SO3
b. How many Kj are involved in forming 3.5 liters of SO3 under STP conditions. (22.4L/mole)
(77.3 Kj released)
5. Fermentation: C6H12O6  C2H5OH + CO2 Find the Delta H/mole of sugar. (-69.4Kj)
6. How many Kj are involved in the production of 2.5L. of Ethanol. Density is .93 g/ml
(1.75e3 Kj)
Chemistry
Energy of Reactions Worksheet IV
Name_____________________ Per. ______
1.
Find the Delta H of Nitrogen Dioxide decomposing to form Dinitrogen monoxide & Oxygen.
(15.7 Kj/m N2O)
2.
If 2.75 Kg of Nitrogen Dioxide is reacting, find the Kj involved. (469 Kj)
3.
If the Potential Energy level of the Nitrogen Dioxide is 850 Kj. and the Ef is 200 Kj,, find the Er
by drawing a PE graph to scale.
(Er = 184.3 Kj)
4. a. Calculate the Heat of Formation of Sulfur Dioxide from its elements. Use the following: (-197Kj)
S + 3/2O2  SO3
Delta H = -395.2 Kj/mole SO3
SO2 + ½ O2  SO3 Delta H = -198.2 Kj/mole SO3
b. How many Kj are involved in forming 3.5 liters of SO2 under STP conditions. (22.4L/mole)
(30.8Kj released)
5. Using Fermentation: C6H12O6  C2H5OH + CO2 and the Delta H found previously, find the
Delta H of the formation of ethanol. .
(-277.7 Kj)
6. How many Kj are involved in the formation of 2.5L. of Ethanol. Density is .93 g/ml. (1.40e4 Kj)
Chemistry Energy of Reactions V
Name _________________________________ Period _________
1. Find the Delta H for the formation of Pentane (C5H12).
2. If 2500 grams of Pentane are formed, find the Kj involved.
3. Draw the Potential Energy Diagram of the formation of Pentane assuming the products can be found at 450
Kj and the Er is 210 Kj.
4. Find the Delta H of this reaction:
Ca(OH)2  CaO + H2O(g)
5. If 750 grams of Calcium Oxide are being produced find the Kj involved.
6. Draw the Potential Energy Diagram of #4 assuming the Activated Complex will be at 450 Kj and the Er is
250 Kj.