Second Day

Today, we extracted artificial colourings form MnMs. Firstly, we removed fluorescent dyes on a string of wool. We then chose 5 MnMs of the same colour and submerged them in acetic acid, to transfer the food colouring into the solution. We decant the coloured solution into another test tube, without transferring any solids. We then placed the string of wool into the tube and added acetic solution. We heated the tube in a boiling water bath for 5mins. After 5mins, we left the wool to dry and placed it into the new test tube, and added 3ml of aqueous ammonia solution. We heated the test tube again until the colour on the wool faded into the solution. The solution is then transferred into a small conical flask. We dotted each standard colorant and our extract onto a silica gel plate. We then transferred the plates into a jar containing conc ammonia. Allowing the plate to develop until the solvent front reached the top.

I learnt that

  • Artificial colourants are subject to government safety regulations 
  • Food colourants are added to food at a low concentration
  • Wool is a binding agent 
  • Wool gives a positive chargeThe colouring cannot be removed using water, and they can only be released in dilute alkali solution 

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