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Analysis of Oxygen Absorber. How can the oxygen absorber absorb oxygen in the food package? What is the composition of the oxygen absorber? In this activity, we will plan and carry out an investigation to find out the chemical nature of the oxygen absorb

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Introduction

Date of experiment: 06/10/2010 Name: Cheung Lap Kwan (6) Group mates: Chan Wing Ho (5) Ho Chun Yung (11) Ho Grace Yan Yu (12) Po Leung Kuk Ngan Po Ling College 2010-2011 Form 6 Chemistry Laboratory Report Title: Chemistry Project: Analysis of an Oxygen Absorber Introduction: In a moon cake package, there is often a packet of oxygen absorber provided with each moon cake. The oxygen absorber is usually used for food storage, because oxygen is the main substance which causes the degeneration of food. Some food contains fat or oil. When the food is exposed in air, the fat and oil may be oxidized by oxygen. This process is called "rancidity" (The main theory of rancidity is not discussed in this report). After the rancidity, the product may be harmful to human. So oxygen absorber is needed to reduce the amount of oxygen in package. Oxygen in air also can facilitate the growth of mold. As we all know, the mold on the food release toxic substances. It is dangerous for us to take in the food contains these toxic substance. When we use oxygen absorber, the concentration of oxygen is decreased. Low oxygen concentration can inhibit the growth of mold. Besides, oxidation of food can cause the colour change of food. ...read more.

Middle

The boiling tube was connected to limewater. Finally the limewater was turned milky. 10. Flame test was done for the oxygen absorber. It was found that golden yellow colour flame was seen. Explanations of the observations above: Explanation of Experiment 2: From the observation, it can be concluded that the oxygen absorber contains some metal which can be attracted by magnet, such as iron (Fe), cobalt (Co) and nickel (Ni). By the introduction, the oxygen absorber can be deduced to contain iron powder. Explanation of Experiment 3: From the observations, it can be deducted that Fe in the oxygen absorber reacted with HCl to give out hydrogen gas (H2). Gas was released after a while because there was an oxide layer on the oxygen absorber, which blocked the Fe to react with HCl. Fe + 2HCl FeCl2 + H2 Fe2O3 + 6HCl 2FeCl3 + 3H2O Explanation of Experiment 4: From the observation, it can be deducted that calcium carbonate (CaCO3) was formed, i.e. carbon dioxide (CO2) was produced during the reaction. The oxygen absorber may contain some carbon (C) or some carbonate (CO32-) solid, because under strong dry heat, both C and CO32- can release CO2. C + O2 CO2 CO32- CO2 + O2- Explanation of Experiment 5: From the observation, it can be deducted that MnO4- disappeared, i.e. ...read more.

Conclusion

Errors and Improvements of experiments: 1. From the experiments above, it was found that an oxide layer was formed on the oxygen absorber powder. It was because the experimental oxygen absorber absorbs a large amount of oxygen before the experiment. This may cause the wrong deduction of the experiment. To improve this problem, in the next time, the experimental oxygen absorber should be kept in closed space, to reduce the amount of oxygen absorbed. 2. In this experiment, the present of sodium ion was supposed present in the oxygen absorber due to the observation of Experiment 10. However, the colour of flame of sodium is similar to that of iron, so it was difficult to test the present of sodium ion accurately. Therefore, the more accurate method is comparing the light emission spectrum between sodium and that of iron. In the spectroscope, we can get an accurate result by their different light spectrums. 3. Of course, the greatest method to determine the composition of oxygen absorber is to inject the oxygen absorber sample in to mass spectrometer. By the peaks in the graph plotted by mass spectrometer, we can know the composition immediately. Conclusion: By the numerous experiments, the oxygen absorber may have iron powder, carbon powder and some sodium chloride salt. Reference: 1. Mitsubishi Gas Chemical Company, INC. (r) http://www.mgc.co.jp/eng/products/abc/ageless/index.html 2. doc88.com http://www.doc88.com/p-90129266292.html 3. Wikipedia Japan http://ja.wikipedia.org/wiki/%E8%84%B1%E9%85%B8%E7%B4%A0%E5%89%A4 --End of the Report-- ?? ?? ?? ?? Page 1 of 7 ...read more.

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