Module name: Physical Chemistry (CP 4117)
Experiment: Heat of decomposition of hydrogen peroxide
Lecturer: Dr Cheow
Name: Loganathan Admin number: 1246102
| Abstract – a precise summary about the whole experiment and report.
| Introduction to the experiment - a brief outline and relevant theory for the experiment and calculation
| Procedure for the experiment – a description of the experiment and how it was done
| Results and discussion – data obtained from the experiment and tabulated results and a practical viewpoint and commenting on the results
| Conclusion – summary of the findings obtained
| References – citation of information and facts from external sources
Our main purpose is to familiarise ourselves with a method to find the heat of decomposition of a compound (hydrogen peroxide). Firstly, we will be looking at information about calorimeter and what it meant by heat of decomposition. Also, we will try to understand why we have to subtract the heat absorbed by the calorimeter to find the heat of decomposition of hydrogen peroxide. Therefore, we found the heat capacity of calorimeter. After that, the enthalpy of decomposition of hydrogen peroxide was calculated by finding the amount of heat lost by solution and the heat absorbed by the calorimeter. Then, the heat absorbed by the calorimeter was subtracted from the heat lost by the solution to determine the amount of heat absorbed by hydrogen peroxide. The enthalpy of decomposition of hydrogen peroxide obtained is -57.9kJ/mol. Finally, we would look at how the results differ from the literature value and understand reasons to why the difference in the values occurs and find methods to prevent this.
1A calorimeter is a device that helps to measure the heat of reaction. There are two types of calorimeters which are usually used. The sophisticated and expensive one, while the other can be easily made and available cheap. The one used for this experiment is the simple and cheap one which is basically a Styrofoam cup because its container walls are well insulated to prevent or reduce the heat change to environment. 2However, the calorimeter would also absorb heat as it is a simple calorimeter and thus it is a necessity to take it into the consideration while doing the calculations to find the heat of decomposition of hydrogen peroxide. Also, the reactants are inside the calorimeter with a lid on top before the reaction has been initiated to prevent heat from escaping or it would cause the results to turn inaccurate. Besides this, a thermometer will be placed inside to constantly monitor the temperature as time progresses. It assists in finding the temperature difference before and after the reaction has completed.
* Heat of decomposition
Heat of decomposition is defined as the breaking down of a single compound (Hydrogen peroxide) into 2 simpler compounds or elements upon the application of heat. Enthalpy of decomposition is thus defined as the amount of heat required to chemically break down a compound. In this experiment we will be trying to find the heat of decomposition of hydrogen peroxide. 4Hydrogen peroxide is an unstable compound. Under normal room conditions, it would break down to water and oxygen. However, the process is very slow to be completed in a normal laboratory period. As a solution, catalyst [Iron (III) nitrate] was introduced. It helps to speed up the process without being consumed itself.
There are basically 2 parts to this experiment, thus 2 procedures. * Heat capacity of calorimeter (Part 1)
A simple calorimeter was firstly made using a thermometer, Styrofoam cup and cover. 30ml of tap water next was poured into the simple calorimeter cup and covered back with the cover and the...
References: 1CaCT, Calorimetry: Measuring heats of reaction. http://www.science.uwaterloo.ca/~cchieh/cact/c120/calorimetry.html [Accessed 19 July 2012]
2Solomon, S., Rutkowsky, S and Boritz, C (2009) Everyday investigations for General Chemistry John Wiley & Sons
4Cool sciences. Heat of decomposition of hydrogen peroxide. http://www.coolscience.org/CoolScience/KidScientists/h2o2.htm [Accessed 22 July 2012]
5About Chemistry. Measurement of Heat flow and Enthalpy Change; Calorimetry - Coffee Cup Calorimetry and Bomb Calorimetry. http://chemistry.about.com/od/thermodynamics/a/coffee-cup-bomb-calorimetry.htm [Accessed 25 July 2012]
3Silcocks, C.G. Physical Chemistry: Thermochemistry and thermodynamics,3rd Ed,: Macdonald & Evans Ltd, 1982.
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