Name: ________________________
Date: ________________________
Lab Partner: ________________________
Lab Section: ________________________
Lab TA: ________________________
CHEM 032 Experiment 2: Chemical Kinetics Analysis of the Iodination of Acetone
Experimental Data
A. Determination of Reaction Orders
Reaction
Mixture
Volume of
4.0 M Acetone (mL)
Volume of
1.0 M HCl (mL)
Volume of
0.0050 M I2 (mL)
Volume of
Distilled H2O
(mL)
I
4
4
8
4
II
2
4
10
4
III
4
2
10
4
IV
4
4
10
2
Reaction
Mixture
Total
Volume
(mL)
Trial 1
Trial 2
Trial 3
Time (sec) Temp (ºC) Time (sec) Temp (ºC) Time (sec) Temp (ºC)
I
20
20
II
25
25
III
25
25
IV
25
25
B. Energy of Activation
Reaction
Mixture
Trial 1
Time (sec) Temp (ºC)
Trial 2
Trial 3
Time (sec) Temp (ºC) Time (sec) Temp (ºC)
Low
Temp
High
Temp
TA: ________________________
E02-9
CHEM 032 Experiment 2: Chemical Kinetics Analysis of the Iodination of Acetone
Calculations
A. Determination of Reaction Orders
1. Calculate the concentration of the components in each reaction mixture. Show at least one
example calculation:
Reaction
Mixture
Concentration of
4.0 M Acetone (M)
Concentration of
1.0 M HCl (M)
Concentration of
0.0050 M I2 (M)
I
II
III
IV
2. Calculate the rate of reaction for every trial of each mixture from Part A. Show at least one
example calculation:
Reaction
Mixture
I
II
III
IV
E02-10
Trial 1
Rate
Trial 2
Rate
Trial 3
Rate
Average
Rate
CHEM 032 Experiment 2: Chemical Kinetics Analysis
of the Iodination of Acetone
Name: ________________________
Date: ________________________
Calculations (continued)
3. Determine the order of reaction with respect to each component:
(Hint – see textbook Example 14.2)
a) Order of reaction with respect to acetone
m = _______
b) Order of reaction with respect to acid
n = _______
c) Order of reaction with respect to iodine
p = _______
4. Write the rate expression for the reaction:
5. Determine the rate constant, k, for each reaction mixture, using the average rates determined
in #2. Show at least one example calculation:
Reaction
Mixture:
Rate constant,
k=
I
II
III
IV
Average
E02-11
CHEM 032 Experiment 2: Chemical Kinetics Analysis of the Iodination of Acetone
Calculations (continued)
B. Energy of Activation
6. Calculate the rate of reaction for every trial of each mixture from Part B. Show at least one
example calculation:
Temperature
Trials
Low
Temp
High
Temp
Reaction
Mixture
Trial 1
Rate
Trial 2
Rate
Trial 3
Rate
Average
Rate
7. Determine the rate constant, k, for each of the temperature trials from Part B. Show at least one
example calculation:
Temperature
Trials
Low
Temp
High
Temp
Reaction
Mixture
Rate constant,
k=
𝟏
8. Data to use for the graph of 𝐥𝐧 𝒌 versus 𝐓 to estimate 𝐄𝐚 , the energy of activation:
Temperature
Trials
Low
Temp
Room
Temp
High
Temp
E02-12
Temp
(K)
1
𝐓
𝑘
ln 𝑘
CHEM 032 Experiment 2: Chemical Kinetics Analysis
of the Iodination of Acetone
Name: ________________________
Date: ________________________
Additional Calculations and Results
9. Determine the energy of activation, 𝐄𝐚 for this reaction. Attach the graph you used to determine
this value. (Hint – see textbook Example 14.7)
Compound
∆𝑯𝒇 ° (kJ/mol)
CH3 COCH3
−248.4
CH3 COCH2 I
−130.6
I2
13.5
I−
−56.0
H+
0.0
10. Use the energies of formation, given in the table to the right, to determine the heat of reaction,
∆𝑯°𝒓𝒙𝒏 for the iodination of acetone. (Hint – recall textbook Example 9.12)
E02-13
CHEM 032 Experiment 2: Chemical Kinetics Analysis of the Iodination of Acetone
Additional Calculations and Results (continued)
11.
a) Having experimentally shown that the rate expression is zero order with respect to iodine,
and given the following, determine which is the rate determining (slow) step in the
mechanism outlined below:
Step 1: __________ (fast or slow?)
Step 1:
𝐂𝐇𝟑 𝐂𝐎𝐂𝐇𝟑 (𝒂𝒒) + 𝐇 + (𝒂𝒒) ↔ 𝐂𝐇𝟑 𝐂𝐎𝐇𝐂𝐇𝟑 + (𝒂𝒒)
Step 2: __________ (fast or slow?)
Step 2:
𝐂𝐇𝟑 𝐂𝐎𝐇𝐂𝐇𝟑 + (𝒂𝒒) ↔ 𝐂𝐇𝟑 𝐂𝐎𝐇𝐂𝐇𝟐 (𝒂𝒒) + 𝐇 + (𝒂𝒒)
Step 3: __________ (fast or slow?)
Step 3:
𝐂𝐇𝟑 𝐂𝐎𝐇𝐂𝐇𝟐 (𝒂𝒒) + 𝐈𝟐 (𝒂𝒒) → 𝐂𝐇𝟑 𝐂𝐎𝐂𝐇𝟐 𝐈(𝒂𝒒) + 𝐇 + (𝒂𝒒) + 𝐈− (𝒂𝒒)
b) Explain your answer:
E02-14
CHEM 032 Experiment 2: Chemical Kinetics Analysis
of the Iodination of Acetone
Name: ________________________
Date: ________________________
Post-Lab Questions
12. Why is knowing the exact concentrations of the acetone, iodine, and acid not critical in
determining the orders of reaction, but using the same stock solutions throughout the experiment
is critical?
13. In determining the energy of activation, why was it prudent to run the slowest trial done at room
temperature in the hot water bath and the fastest trial done at room temperature in the cold water
bath?
E02-15
CHEM 032 Experiment 2: Chemical Kinetics Analysis of the Iodination of Acetone
Results & Discussion: The main experimental result(s) should be clearly summarized and related back
to the purpose of the experiment. Should also include a brief discussion of experimental error when
applicable.
E02-16