Warmth of decomposition of hydrogen peroxide

Abstract

Our main goal is to acquaint ourselves with a method to get the heat of decomposition of the compound (hydrogen peroxide). Firstly, we will be taking a look at information about calorimeter and what meant by simply heat of decomposition. Also, we will endeavour to understand so why we have to take away the heat consumed by the calorimeter to find the high temperature of decomposition of hydrogen peroxide. Consequently , we found the heat capability of calorimeter. After that, the enthalpy of decomposition of hydrogen peroxide was determined by finding the amount of heat lost by simply solution plus the heat assimilated by the calorimeter.

Then, the heat absorbed by the calorimeter was subtracted from the heat lost by the solution to determine the quantity of heat consumed by hydrogen peroxide. The enthalpy of decomposition of hydrogen peroxide obtained is usually -57. 9kJ/mol. Finally, we would look at how the results vary from the literature value and understand good why the difference in the beliefs occurs and locate methods to stop this.

Advantages

* Calorimeter

1A calorimeter is a unit that helps to measure the warmth of response. There are two sorts of calorimeters which are generally used. The sophisticated and expensive one, even though the other can be easily produced and available cheap. The one used for this kind of experiment is definitely the simple and low-cost one which is basically a Styrofoam cup since its textbox walls are very well insulated in order to avoid or decrease the heat change to environment.

2However, the calorimeter would likewise absorb heat as it is an easy calorimeter and so it is a requirement to take it into the consideration while performing the computations to find the temperature of decomposition of hydrogen peroxide. Likewise, the reactants are inside calorimeter having a lid on top before the reaction has been started to prevent temperature from avoiding or it will cause the results to change inaccurate. Besides this, a thermometer will be placed inside to frequently monitor the temperature as time advances. It aids in finding the temperature difference before and after the response has finished.

* Heat of decomposition

Heat of decomposition is identified as the digesting of a solitary compound (Hydrogen peroxide) in to 2 simpler compounds or perhaps elements after the application of heat. Enthalpy of decomposition can be thus understood to be the amount of temperature required to chemically break down a compound. Through this experiment we will be trying to find heat of decomposition of hydrogen peroxide. 4Hydrogen peroxide is usually an unstable mixture. Under normal room conditions, it would break up to water and air. However , the method is very slower to be completed in a normal lab period. As a solution, catalyst [Iron (III) nitrate] was introduced. It helps to increase the process without having to be consumed on its own.

Procedure

There are basically two parts to the experiment, therefore 2 methods.

* Temperature capacity of calorimeter (Part 1)

An easy calorimeter was firstly manufactured using a thermometer, Styrofoam cup and cover. 30ml of tap water following was added into the basic calorimeter cup and covered back together with the cover and the thermometer. It was left in the room temp for about 5-10 minutes prior to recording the temperature to the nearest 0. 5oC.

An additional 30ml of water was poured to a 250ml beaker and heated up using a hot plate until the temperature was about 20oC more than room temp which would means regarding 44-50 occitan. Then, the heated normal water was in order to stand for 1 minute as well as its temperature was written immediately towards the nearest 0. 5oC and poured entirely into the calorimeter. The cover was protected over it together with the thermometer along. The cup was subsequent swirled once. The temperature was discovered for 4 minutes and was recorded every 15 seconds.

* Enthalpy of decomposition of hydrogen peroxide answer (Part 2) After the first part of the test was finished, the calorimeter and the thermometer were dried out completely. 50ml of 1. 0M hydrogen peroxide (H2O2) was then cautiously measured and poured into the calorimeter. The cover was then changed along with the thermometer. The solution was swirled when and temperature was recorded each and every minute pertaining to 4 a few minutes. At the 5-minute mark, the cover and the thermometer were removed. 10ml of 0. 50M Flat iron (III) nitrate [Fe(NO3)3] was measured and added in the calorimeter that contains the hydrogen peroxide.

Temperature was following measured for 5. five minute draw and for every succeeding tiny till a total of 20 minutes. A temperature or time curve was after that constructed with the data obtained from the experiment to ascertain change in heat. Next, enthalpy of the decomposition of hydrogen peroxide was calculated. A starting heat can be found by simply extrapolating the 5 points prior to adding the catalyst to the stage of mixing. The final temperature can also be found by extrapolating the geradlinig portion of the graph to the point of mixing.

5. Discussion

While the materials value stated in the data linen, the heat of decomposition in the hydrogen peroxide is -94. 6kJ/mol. However the value received was simply -57. 9kJ/mol. This was for the reason that heat continues to be lost for the surroundings about outside the calorimeter. The calorimeter is not perfect and simple and thus it is cover is usually not appropriate and does not totally cover the top of the Styrofoam cup, departing a small beginning. The heat could have escaped from the calorimeter through here. Besides this, the experiment was done for a long period of 20 minutes. The longer the time, there is more hours for the warmth to escape in the imperfect calorimeter. This leads to a lesser temperature than expected to be recorded because time moves along. This leads to decrease temperature difference leading to a lesser heat of decomposition of hydrogen peroxide to be from the reaction.

One more possibility of burning off heat took place during the addition of the Flat iron (III) nitrate as catalyst inside. Once it was added, the reaction was increased rapidly producing a large amount of heat. However , the cover was not covered on time and was sluggish which generated a significant volume of heat to get lost for the surroundings. As well, the heat shown has not been accurate due to the poor calibration of the thermometer. Often estimation to the local 0. 1oC has to be carried out when recording the effects. Due to the use of an imperfect calorimeter, the results attained were inaccurate. Thus we could improve this kind of experiment through a perfect calorimeter which will help to lower heat by escaping from the calorimeter significantly and also reduce the heat by being assimilated by the calorimeter itself. 3One perfect case in point would be the usage of the adiabatic calorimeter.

The calorimeter’s yacht is basically surrounded by a jacket containing water. Therefore , the temperature of which will automatically end up being same as the temperature in the vessel. Because the temperature in the reacting program and the natural environment is the same, there is no high temperature passed in either path. This would bring about much more correct results. Besides this, we are able to also make an effort to reduce the period taken to a quarter-hour. I would recommend this because the longer the time used for the experiment, the bigger the possibilities intended for the calorimeter to lose heat to the environment. Hence, by reducing the time, the possibilities of losing heat is minimised. Apart from this, we are able to also use a thermometer with a finer calibration to note the slightest big difference in the temp which could cause the significant modifications in our results received.

Conclusion

From your results obtained, I can conclude that the using the simple calorimeter is no ideal choice due to likelihood of losing temperature to the surroundings. A sophisticated and better calorimeter has to be applied. 5Styrofoam glass calorimeter just isn’t recommended just for this decomposition response as it entails production of your gas, O2 which can get away from the glass easily.

Besides this, i was better familiarised with a solution to find the warmth of decomposition of chemical substances with the use of calorimeter. It can also be concluded that hydrogen peroxide is not a stable chemical substance and fights slowly in room temperature and pressure and is speed up by the usage of catalyst. In total, the principles obtained from the experiment are certainly not useful as a result of severe errors which took place during the experiment mainly as a result of apparatus utilized.

References

1CaCT, Calorimetry: Measuring heats of reaction. http://www.science.uwaterloo.ca/~cchieh/cact/c120/calorimetry.html [Accessed nineteen July 2012] 2Solomon, S., Rutkowsky, S and Boritz, C (2009) Every day investigations intended for General Chemistry John Wiley & Kids 4Cool sciences. Heat of decomposition of hydrogen peroxide. http://www.coolscience.org/CoolScience/KidScientists/h2o2.htm [Accessed twenty-two July 2012] 5About Chemistry. Way of measuring of Heat stream and Enthalpy Change; Calorimetry ” Coffee Cup Calorimetry and Bomb Calorimetry. http://chemistry.about.com/od/thermodynamics/a/coffee-cup-bomb-calorimetry.htm [Accessed 25 September 2012] 3Silcocks, C. G. Physical Chemistry: Thermochemistry and thermodynamics, 3rd Male impotence,: Macdonald & Evans Ltd, 1982.

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