CHEM 3493 - Experiment # 1 -Molecular theories

Heats of combustion: Parr oxygen bomb calorimetry, calibration and measurements

LIST:

1. Notebook: pre-lab report, all results from lab notebook, all work done in the lab written in lab notebook

BEFORE THE EXPERIMENT: Read CAREFULLY EXPERIMENT 6 and related material from the textbook. In this experiment we measure heats of combustion using bomb calorimeter, we will use benzoic acid as standard. You will need to learn how to use bomb calorimeter and how to prepare sample pallets and connect them with wire. OBSERVE ALL SAFETY RULES IN THE LAB!  Identify the pressure limits for filling the bomb with oxygen and other parameters, learn how to start the combustion using electrical wire, and how to very precisely measure temperature. WRITE DOWN DETAILED LIST OF STEPS /Procedure FOR YOUR EXPERIMENT.

You will also read and become familiar with the Thermodynamical observables and principles as well as with the basic physico -chemical principles on which the  models for heat  of combustion is based (see textbooks and manuals. You should calculate all theoretical and experimental values using the expressions in the book . The needed data should also be available in the textbbok, PChem book or in the literature.

2. Mathematica (or similar ): all calculations and uncertainty calculations, with the data

* You will write all needed expressions - see textbook and this page to find what you need to calculate and model in Mathematica - and do the calculations before submission of results to this webpage. In the Mathematica program assign the values to the standard physical constants first (example: R etc). Make sure that all input values are in real number format ("with decimal point"). USE THE CORRECT and CONSISTENT SET of UNITS The dimensional equations could be calculated the same way as numerical-but be careful.

Use Mathematica for the calculation of the propagation of uncertainties expressions. You can practice the model calculations and uncertainty calculation using available data from first sets of experiments. Make a Mathematica  example file at the beginning of experiment to see how to do the modeling and calculations . You can use Excel in this case too.

3.This web submission

Fill in the blank fields below with your measured data, results of (Mathematica) modeling, simulations  and calculations. After you have re-checked that all of your values are entered correctly, print out a hard copy of confirmation page for your record - all is to be submitted with your pre-lab and the copies of lab-notebook sheets. You are allowed to submit data more than once-if you make entry error; so make sure your last entries are correct.   Then click on the submit button.

 

4. Report in .doc format (abstract, intro, results&discussion, conclusions, references)

You can use the calculations from Mathematica and cut-paste copy into report. Make sure that each calculation step is clearly presented.

*You can attach/submitt by e-mail with CHEM3493-experiment#-YOUR NAME all on that list, except the copies from notebook. Also ,when needed, computer generated work (acquired data in files, images, including all instrument-software, LabView, Mathematica, Excel files, Gaussian03 or PeakFit files etc. ).

Additional post-experiment work (experiment # 6) will include QM software based (Gaussian) modeling of the thermodynamic properties of these molecules. You will read about these calculations and will be shown how to perform the calculations on the GridChem or/and LSU parallel computer system Use Gaussian 03 example file for the additional report.

Additional post-experiment work (experiment # 5) will include instrumentation study and development.


Name:
Group:
Instrument (s) used
Chemicals used
TA:

Pre-lab information:

Write down combustion equation for naphthalene
What is the oxygen pressure in the bomb
What is the MAX precision of the thermometer
What is the specific/g energy of combustion of Fe wire
What is the literature values for the heat of combustion for benzoic acid
What is the Dn value for the oxidation of your standard
What is the time period you plan to acquire the temperature readings
Which additional compound are you investigating ?
What is the literature value for the heat of combustion for naphthalene

*

A -Table 1- data for masses and temperatures
 
 

BA.

 s Naphthalene s Other s
Mass of substance
Mass of wire
Mass of wire + substance
Mass of wire after the combustion
Mass of wire combusted/burned
Tf
Ti
(dT/dt)f
(dT/dt)i
ti
td
tf
           

B Table 2 - Results
 
   DT  s Cs s DH DE +- s
              BA 1 +_
BA 2
+_
Naphthalene 1
+_
Naphthalene 2
+_
Average BA
+_
Average Naphthalene
+_
Other 1
+_
Other 2
+_
Average other
+_

C - percentage discrepancy

  BA Naphthalene Other
DE literature      
DE measured/average      
%      
       


Print and save a hard copy of this page and save the confirmation page, for your records.


 
 


 
 



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Louisiana State University, Department of Chemistry.
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