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Colorimetry Experiment - I will investigate and observe the amount of concentration of food dye in cherryade.

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\\wss1caterham\nievettha.r$\My Documents\Applied Science\2.jpg Colorimeter Background Information - Colorimeter A colorimeter is an apparatus for measuring heat quantities. A colorimeter is calibrated using known concentrations of a coloured solution. The part of the light is absorbed when light is passed through a medium and as a result, there is a decrease in how much of the light reflected by the medium. A colorimeter measures the change that is occurred so that people that are using the colorimeter can analyse the concentration of a particular substance in that medium. The more concentrated the solution is, the more light that will be absorbed. Colorimeter has three main parts which are the light source, a cuvette and a photo resistor. The cuvette holds the solution and the colorimeter is equipped with coloured filters to produce coloured light. The light that is transmitted by the solution in the cuvette is detected by a photo cell and it produces signal such as the analogue and digital signals that can be measured. The more light that hits the photocell, the higher the current it produces. Colorimeters can also be used in laboratory testing and they are useful for on-site tests. When you use a colorimeter, you will need to calibrate the instrument and use it to determine the absorbance values of several standard solutions containing a solute at known concentrations. When the light of a particular colour is directed through a chemical solution, some of it is absorbed and then some of it is transmitted. ...read more.


Risk Assessment Equipment/Method Hazard Risk consequence/ Chance Steps to minimise risk How severe was this risk? (Hazard x risk) Accidentally drinking sample of cherryade or the food dyes. There is a 3/10 chance of this potential hazard because you might spill it and splash it in your mouth. This could possibly cause food poisoning and this might be harmful to the person as it might result the person in serious conditions. There is a low chance which means there is a 1/10 chance of this hazard occurring because you will be instructed with the instructions of what to do with the sample. Make sure you know the instructions that are guided to you in the lab and follow that to reduce the risk. An overall risk of this hazard happening is: 3/10 x 1/10 = 3/100. Breaking test tubes There is a 3/10 chance of this potential hazard because you might drop it or it might be on the table and it might fall on the floor. Cuts and Infections can cause when test tubes are broken. There is a medium chance which means there is a 5/10 chance of this hazard occurring. Use a test-tube rack to minimise this risk as the test tubes will be prevented from breaking and it will be safer to the people working with it in the lab. An overall risk of this hazard happening is: 3/10 x 5/10 = 15/100. Chemical Spillage There is a 9/10 chance of this potential hazard because people are more likely to spill chemicals when working with it in the lab. ...read more.


To improve this, we used another colorimeter that was functioning properly which gave me accurate results for the experiment that I have carried out. Another problem that came up was preparing the concentrations/serial dilution and this affected the experiment because when preparing the concentrations, there was a problem with serial dilution. The concentration will be more inaccurate with every dilution as we weren?t using 80ppm for each dilution, we added distilled water for each concentration and this diluted. To improve this problem, we could dilute the 80ppm concentration for each separate concentration to get more accurate results and to make the experiment reliable. Furthermore, using a measuring cylinder to measure volume was another problem and this affected the experiment as this was accurate to plus/minus one graduation and small measurement. An improvement for this is we could use a syringe with a finer scale. Smaller graduation or another way of improving is to use a measuring pipette to get an accurate result. Finally, holding the cuvette is another problem and this affected the experiment because when holding the cuvette, you have to hold it on the top four corners instead of holding it in the middle because this was a problem that came up while doing the experiment, If you don?t hold the cuvette properly, then you wouldn?t get an accurate result for the experiment. In order to improve this, I would hold the top four corners of the cuvette so that it would give accurate results without any fingerprint blocking the transmit of light. ...read more.

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