Tests and the Colorimeter

• Describe the steps in identifying lipids and state the positive result

  mix the sample with ethanol

  mix the solution with water then shake

  white emulsion layer formed therefore lipid is present
• How can we use a colorimeter to do a quantitative benedicts test

  colorimeter measures the absorbance or transmission of light by a coloured solution

  more concentrated solution more light absorbed/ less light is transmitted

  compare to data table (known concentration vs trans value)
• Explain how a positive result is formed in benedicts test

  Reducing sugars react with blue Cu2+ to make brick red Cu+
• How do you calculate the volume of stock solution required 


  Desired concentration/concentration of stock x volume wanted