Qualitive Tests For Molecules

Question 1

Biuret (protein)

Answer 1

1. NaOH (aq)
2. CuSO4 (aq)
   + Lilac
   - Blue

Question 2

Iodine (starch)

Answer 2

1. Add Iodine in KI (aq)
   + blue/black
   - brown/orange

Question 3

Emulsion (lipid)

Answer 3

1. Ethanol
2. Pour solution into water
   + cloudy/milky
   -colourless

Question 4

Benedict’s (reducing)

Answer 4

1. Add Benedict’s
2. Heat in a water Bath that’s brought to a boil
   + brick red ppt
   - blue (aq)

Question 5

Benedict’s (non-reducing)

Answer 5

1. Dilute HCL
2. Put in a water Bath brought to a boil
3. Neutralise With NaHCO3
4. Add Benedict’s
5. Place in a water bath brought to a boil
   + brick red ppt
   - blue (aq)

Question 6

Test strips (glucose)

Answer 6

1. Dip test strip in
   + colour change (check conc against chart)
   - no change

Question 7

Other ways to measure conc

Answer 7

Biosensors, colorimetry