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

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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. The more concentrated the solution is, the more light will be absorbed, which can see be seen in the difference between the light at its origin and after it has passed through the solution. To get the concentration of an unknown sample, then several samples of the solution in which the concentration is known are first tested. These will be plotted on a graph such as scatter with the concentration at one axis and the absorbance on the other side to create a calibration curve. 

Situation

I am working for the trading standards as a scientist. I will investigate and observe the amount of concentration of food dye in cherryade. I am investigating as too much food dye was possibly used in a drinks company and using too much food dye can be harmful. I will be testing to see if the concentration of the food dye is within the safe limits. The acceptable limit is 18ppm I will be testing to see if the concentration of the food dye is above the limit, then it’s not safe.

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Equipment 

Diagram

Method

  1. Set equipment up as shown in diagram
  2. Pour distilled water in to the cuvette
  1. Hold the cuvette by the top so that there won’t be any finger marks
  2. Place the cuvette into the colorimeter and close the lid
  3. Adjust the light intensity dial on the colorimeter so it reads just below 100% transmittance
  4. Put some of the 80ppm food dye into a clean cuvette using ...

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