qualitative testing

• What is the purpose of the Biuret test?

  To test for the presence of proteins
• What is the first step in the Biuret test?

  Add sodium hydroxide solution
• What color change indicates a positive Biuret test?

  Color change from blue to purple
• What does the iodine test detect?

  Starch
• What is the procedure for the iodine test?

  Add iodine in potassium iodide solution
• What color change indicates a positive iodine test?

  Color change from brown-orange to blue-black
• What does the emulsion test detect?

  Lipids
• What is the first step in the emulsion test?

  Add ethanol
• What indicates a positive result in the emulsion test?

  The solution goes a milky color
• What is the purpose of Benedict's test?

  To test for reducing sugars
• What is the first step in Benedict's test for reducing sugars?

  Add Benedict's reagent to a sample
• What happens to the sample during Benedict's test for reducing sugars?

  The sample goes from blue to brick red precipitate
• What does the color change in Benedict's test indicate?

  The concentration of reducing sugars
• What is the procedure for testing non-reducing sugars using Benedict's test?

  Add dilute HCl, heat, neutralize, then perform Benedict's test
• What is the final step in testing for non-reducing sugars after neutralization?

  Perform Benedict's test for reducing sugars
• What do test strips detect?

  Glucose
• How do you use test strips for glucose testing?

  Dip the test strip in the solution
• What should you do after dipping the test strip in the solution?

  Compare the color change to a chart of known color changes
• What are the steps of the Biuret test for proteins?

  1. Add sodium hydroxide solution.
  2. Add copper (II) sulphate solution.
  3. Observe color change from blue to purple.
• What are the steps of the iodine test for starch?

  1. Add iodine in potassium iodide solution.
  2. Observe color change from brown-orange to blue-black.
• What are the steps of the emulsion test for lipids?

  1. Add ethanol.
  2. Pour solution into water.
  3. Observe solution going a milky color.
• What are the steps of Benedict's test for reducing sugars?

  1. Add Benedict's reagent to a sample.
  2. Heat in a water bath brought to a boil.
  3. Observe color change from blue to brick red precipitate.
• What are the steps for testing non-reducing sugars using Benedict's test?

  1. Add dilute HCl and heat.
  2. Neutralize with sodium hydrogen carbonate.
  3. Perform Benedict's test for reducing sugars.
• What are the steps for using test strips to detect glucose?

  1. Dip test strip in solution.
  2. Observe color change.
  3. Compare to chart of known color changes.