- albumen solution or egg white
- starch solution
- water
- Benedict’s solution
- Fehling’s solution
- marking pen to mark the test tubes
- thermometer
- 10 ml syringe or measuring cylinder
Safety precautions:- Follow the safety procedures (listed in Chapter 1) when lighting your Bunsen burner.
Do not light it in a shelf or near any lights and remove all notebooks, papers and excess
chemicals from the area. Tie back any long hair, dangling jewelry and loose clothing
and never leave an open flame unattended while it is burning. - When heating your test tubes in the boiling water in the beakers ensure that the mouth
of the test tubes point away from you and fellow learners. - When handling the test tubes, especially when they are hot, use a test tube holder and
wear goggles.
Method:Prepare a water bath by filling a beaker to the halfway mark with water. Place the beaker on
a tripod stand over a bunsen flame as shown in Figure 2.12. This will serve as your water
bath.Whilst waiting for the water to boil or the water to reach temperature in the water bath, carry
out the following instructions:- Label the test-tubes 1–4.
- Using the syringe or measuring cylinder, add the following to the test tubes.
- Test tube 1: 5 ml of 1% starch solution
- Test tube 2: 5 ml of 10% glucose solution
- Test tube 3: 5 ml 1% albumen solution
- Test tube 4: 5 ml water.
- Add 5 ml Benedict’s solution to each tube.
- Place the test-tubes in the beaker of hot water on the tripod.
- Use a thermometer to monitor the water temperature and adjust the flame to maintain
the water temperature at approximately 50◦C. - If using the water bath, place the test tubes into the test tube rack and place into the
water bath with temperature set to 50◦C. - After about 5 minutes, when a colour change has occurred in some of the test tubes,
extinguish the flame, or remove the test tubes from the water bath. - Place the four tubes in a test-tube rack and compare the colours.
34 2.4. Organic compounds