MODIFICATIONS TO " QUALITATVE TESTS FOR CARBOHYDRATES"
Use only sucrose, glucose, xylose , fructose and starch for the experiment. Test the unknown along with the known solutions.
Do not perform : Molish  and Bial's tests.
SET THE HOT WATER BATHS  IN THE FUME HOODS!
Before you do anything:
1.  Label 6 test tubes: xylose, sucrose, fructose, glucose, starch, unknown   (use permanent markers provided),
 and
2.  Prepare the hot water bath in a 400 ml beaker on a) ring/wire gauze/bunsen burner or b) a hot plate.
a) Prepare a ring stand and secure a medium ring to it. Place a wire gauze with a ceramic center on the ring. Position  a bunsen burner underneath the wire gauze in such a way, that after lighting and adjusting the flame,  the ceramic center should be about 1 inch above the tip of the inner cone of the flame. Pour about 250 ml of tap water  into a 400 ml beaker and place the beaker on the wire gauze.  Take a large ring and secure it to the stand so that the beaker was  in the center.
b) Put the hot plate on a ring stand’s platform and attach a large ring to the stand. Place a 400 ml beaker, filled with 150 ml tap water into the ring,  but do not try to suspend the beaker. Make sure that the beaker stands firmly on a hot plate (no need for any wire gauze here).  Turn the Heat dial to setting 8.  Reduce the heat later, when water starts boiling
 

TESTS
1. Perform the KI/Iodine test for starch on the spot plate instead of a test tube:
- place  3 drops of each tested carbohydrate and  unknown in the wells of the spot plate. To each well, add 1 drop of the I2/KI reagent.  Record the observations, discard the contents of the plate into a waste container and wash it.

2. Barfoed’s test:
Transfer 5 drops of each tested solution to a labeled  test tube. Add 1 ml of the Barfoed’s reagent to each. (use the provided calibrated plastic pipet to measure volume). Place the test tubes in the boiling water bath. Remove after 5 minutes. Observe and record the presence of a ppt. Replace the test tube that did not have any ppt in the bath and let them heat for another 5 minutes.
Discard the contents of the test tubes. Wash  teh test tubes and dry them using a paper towel wick.

3.  Seliwanoff’s test:
Transfer 3 drops of each tested solution to a labeled  test tube. Add 5 drops of water and 3 ml of Seliwanoff’s reagent to each tube. Place the test tubes in the boiling water bath. Remove after 2 minutes. Do not let the tubes stay in bath for longer than 2.5 min!!!!  Record the results. Discard the contents of the test tubes in to the proper waste container. Wash  the test tubes and dry them with a paper towel wick.

4. Benedict's test:
Transfer 3 drops of  each tested solution to a labeled  test tube. Add 1 ml of Benedict's solution to each test tube. Place the test tubes in the boiling water bath. Remove them after 2 minutes, place in the test tube rack.
Record the results. Discard the contents of the test tubes in to the proper waste container and wash the test tubes.

Do not do post lab question # 2, 4 and 5 (1)(3)  = Postlab questions due: 1, 3, 5(2), 5(4)