Upload
truongkhanh
View
214
Download
1
Embed Size (px)
Citation preview
THE J COMPANY
615 McCallie Avenue
College of Engineering and Computer Science
Chattanooga, TN 37403
Jordan Hughes - [email protected]
John Thetford - [email protected]
Jonathan Cain - [email protected]
To: Drs. Henry and Ennis
From: J Project Engineers
Re: Reaction Studies Report
Date: December 3, 2013
The J Company has recently been assigned an experiment to investigate the impact of
temperature and concentration on the rate of reaction. The rate of reaction was also investigated
after the platinum catalyst had been used 31 times.
The decomposition of hydrogen peroxide is a thermodynamically favorable process. This
reaction will occur naturally at a prescribed rate that is dependent on temperature. A platinum
catalyst is used in this experiment.
The J Team’s findings are compiled in the report below. The J Team had assistance from Team
Gray in the junior. Some of the data collected and analyzed from the junior team was used to
help compile the report below. Please give any and all necessary feedback and comments to
better this report.
Thank you,
J Project Engineers
Rate of Reaction Studies
UTC College of Engineering and Computer Science
ENCH 4350
J Team
Jordan Hughes
Jonathon Cain
John Thetford
Report Submitted To: Drs. Henry and Ennis
December 3, 2013
ABSTRACT
The purpose of this experiment is to study the reaction kinetics of a 3% hydrogen peroxide
solution. The experiment will allow for the effects of temperature and concentration on the
reaction completion time to be investigated. The over the counter contact solution used stated to
not use the container after 31 uses. Therefore, the effectiveness of the platinum catalyst container
after 31 uses was also investigated.
After completing each trial, it was concluded temperature and concentration affect the reaction
completion time of the reaction of hydrogen peroxide with the platinum catalyst. An increase in
temperature will decrease the average reaction completion time. The more dilute the hydrogen
peroxide with water, the faster the average reaction completion time. After the platinum catalyst
container has been used 31 times, its effectiveness is decreased. This was expected because the
over the counter contact solution used stated on the box that it should not be used after 31 uses.
Table of Contents
ABSTRACT .................................................................................................................................................. 3
INTRODUCTION ........................................................................................................................................ 5
THEORY ...................................................................................................................................................... 6
EQUIPMENT ............................................................................................................................................... 7
PROCEDURE ............................................................................................................................................... 9
RESULTS ................................................................................................................................................... 10
DISCUSSION OF RESULTS ..................................................................................................................... 15
CONCLUSIONS......................................................................................................................................... 16
APPENDIX ................................................................................................................................................. 17
Tables and Figures Table 1: Average reaction completion time for pure hydrogen peroxide. ................................................. 10
Table 2: Average reaction completion time for the 1:1 dilution. ............................................................... 10
Table 3: Average reaction completion time for the 1:2 dilution. ............................................................... 11
Table 4: Average reaction completion time for 1 Celsius. .......................................................................... 11
Table 5: Average reaction completion time for 50 Celsius. ........................................................................ 12
Table 6: Average reaction completion time for 75 Celsius. ........................................................................ 12
Table 7: Uncertainty Calculation Table. ...................................................................................................... 17
Figure 1: 3% Hydrogen Peroxide solution used during the experiment. ...................................................... 7
Figure 2: Glass beaker containing the platinum catalyst containers on the Fisher Scientific Isotemp
stirring hot plate. .......................................................................................................................................... 7
Figure 3: Close up of the reaction taking place in the platinum catalyst container. .................................... 8
Figure 4: Effects of Temperature on the Reaction Completion Time. ........................................................ 13
Figure 5: Effects of Concentration on the Reaction Completion Time. ...................................................... 13
Figure 6: Investigation of the platinum catalyst after 31 uses. .................................................................. 14
INTRODUCTION
The purpose of this experiment is to study the reaction kinetics of a 3% hydrogen peroxide
solution. The experiment will allow for the effects of temperature and concentration on the
reaction completion time to be investigated.
The rate of a chemical reaction depends on many variables such as temperature, concentration,
pressure and presence of catalysts. Two easily measureable changes to a reaction are the
adjustment of temperature and concentration. This experiment measures the differing reaction
completion times based off of differing temperature and concentrations of the reactants.
The reaction studied is the catalytic decomposition of hydrogen peroxide.
2��������→ 2����� �����
It is a spontaneous reaction at normal conditions, but is very slow. Using a catalyst the reaction
can proceed at a rate that is easily measurable and visually cueing as to when the reaction is
complete.
The 3% hydrogen peroxide solution is a common over the counter contact cleaning solution. A
platinum catalyst container is included in each box of cleaning solution. The hydrogen peroxide
solution reacts with the platinum catalyst. The reaction completion time will vary with
differences in temperature and concentration.
The over the counter contact cleaning solution gives the warning to not use the platinum catalyst
container after 31 uses. This was investigated by senior management and the junior team. The
same platinum catalyst container was used for all trials.
THEORY
The catalytic decomposition of hydrogen peroxide reaction is shown below.
2��������→ 2����� �����
The decomposition of hydrogen peroxide is a thermodynamically favorable process. This
reaction will occur naturally at a prescribed rate that is dependent on temperature or
concentration. When a catalyst is introduced to the reaction, the rate will speed up to the point
that bubbling will be visible. The catalyst used during this reaction is platinum.
The decomposition of hydrogen peroxide is a spontaneous reaction at standard temperature and
pressure. The change in entropy and enthalpy of the reaction dictates that the reaction will occur
spontaneously. ∆�� ��������� � � ���������
∆�� �2��285.83� 0� � �2��187.78�� �196.1 "#$�
∆�% ��������� � � ���������
∆�% �2�69.91� 205.138� � �2�109.6�� 125.758 #& ∗$�
The entropy is positive, indicating an increase in disorder of the system. The enthalpy is
negative indicating that heat is produced by the reaction. Gibbs energy of reaction:
∆�( ∆�� � )∆�%
Results in a ∆�( of -233,560 J/mol., confirming that the reaction is spontaneous at normal
pressure and temperature.
EQUIPMENT
The equipment used during the decomposition of hydrogen peroxide experiment was a glass
beaker, 10 mL graduated cylinder, precision balance, Fisher Scientific Isotemp stirring hot plate,
a platinum catalyst container, potassium iodide to control temperature, and a stop watch. The
precision balance used was a Mettler XP Analytical scale. Potassium iodide requires energy to
break the bonds between the potassium and iodine ions which are received from the water. This
will cause the temperature of the water to drop. The potassium iodide was only used for the
temperature trials at 1°C. The Fisher Scientific Isotemp stirring hot plate was used for the
temperature trials at 50 °C and 75°C.
Figure 1: 3% Hydrogen Peroxide solution used during the experiment.
Figure 2: Glass beaker containing the platinum catalyst containers on the Fisher Scientific
Isotemp stirring hot plate.
Figure 3: Close up of the reaction taking place in the platinum catalyst container.
PROCEDURE
The procedure allowed for repeatability of the experiment.
1. Measure 6 mL of the hydrogen peroxide solution into a graduated cylinder.
2. Pour the contents into the platinum catalyst and immediately weigh the solution to the
nearest 0.001 g on a precision balance. Start the timer immediately.
3. Record the initial weight.
4. Record the reaction completion time for three trials at 1°C, 50°C, and 75°C, and three
trials of pure hydrogen peroxide, 1:1 dilution, and 1:2 dilution.
5. After the above 18 trials, continue running trials at 75°C and at a 1:2 dilution until more
than 31 trials have been completed. Be sure to use the same platinum catalyst container
for all trials.
6. Compile all of the data into tables and graphs.
7. Investigate the effects of temperature, concentration, and 31 uses on the reaction
completion time.
RESULTS
The data for each trial of the decomposition of hydrogen peroxide is shown in Tables 1-6 below.
Sample calculations of the uncertainty can be found in the Appendix.
Table 1: Average reaction completion time for pure hydrogen peroxide.
Table 2: Average reaction completion time for the 1:1 dilution.
Table 3: Average reaction completion time for the 1:2 dilution.
Table 4: Average reaction completion time for 1 Celsius.
Table 5: Average reaction completion time for 50 Celsius.
Table 6: Average reaction completion time for 75 Celsius.
Figure 4: Effects of Temperature on the Reaction Completion Time.
Figure 5: Effects of Concentration on the Reaction Completion Time.
Figure 6: Investigation of the platinum catalyst after 31 uses.
DISCUSSION OF RESULTS
Figure 1 above indicates that temperature has an effect on the reaction completion time. An
increase in temperature will speed up the reaction completion time. Figure 2 above indicates that
concentration has an effect on the reaction completion time. The more dilute the hydrogen
peroxide solution, the faster the reaction completion time.
Figure 3 above shows the investigation of 31 uses on the platinum catalyst container. This was
investigated at different temperatures only. After 10 trials at 0°C, 50°C, and 75°C, the remainder
of the trials was performed at 75°C for time purposes. The same platinum catalyst was used for
all trials. From Figure 3, it can be seen that after the platinum catalyst has been used 31 times, its
effectiveness slowly starts to be altered. This can be seen by the squares. The reaction
completion time is longer that previously recorded at 75°C after 31 uses.
CONCLUSIONS
After completing each trial, it was concluded temperature and concentration affect the reaction
completion time of the reaction of hydrogen peroxide with the platinum catalyst. An increase in
temperature will decrease the average reaction completion time. The more dilute the hydrogen
peroxide with water, the faster the average reaction completion time. After the platinum catalyst
container has been used 31 times, its effectiveness is decreased. This was expected because the
over the counter contact solution used stated on the box that it should not be used after 31 uses.
APPENDIX
Sample Calculation of the Uncertainty of Reaction Time
Table 7: Uncertainty Calculation Table.
95 % Confidence
(Xmax – Xmin)*t/n
= (14.00 – 13.41)*2.9/3.0
= 0.57 min