Lab Report Info

Lab Report

Procedure 6.1:
Perform Benedict’s test for reducing sugars.

Introduction:
Benedict’s tests allows for the detection of the presence of reducing sugars. All monosaccharides are reducing sugars since all of them have active carbonyl group. Some disaccharides that are exposed to a carbonyl group are also reducing sugars but less reactive than monosaccharides. By mixing the sugar solution with Benedict’s solution and heating them, a redox reaction will occur. The copper (II) sulphate present in Benedict’s solution reacts with electrons from aldehyde or ketose group of reducing sugars to form cuprous oxide, a red brown precipitate.

Materials:
The materials used in order to detect starches was: test tubes, distilled water, Benedict’s solution, starch were used.

Negative Control: H20
Positive Control: Starch

Obtain nine test tubes and number them 1-9
Add to each tube the materials to be tested. Add 2ml of Benedict’s solution to each tube.
Place all the tubes in boiling water- bath for 3 minutes and observe color changes during this time.
After 3 minutes , remove the tubes from the water- bath and give the tubes ample time to cool to room temperature. Record the color of their contents.

Procedure 6.2:
Perform the iodine test for starch

Tube
Solution
Benedict’s Color Reaction
Iodine Color Reaction
1
10 drops onion juice
No change
Blue->Black w/white

No change
2
10 drops potato juice
Precipitation
Yellow-> blue
3
10 drops sucrose solution
No change
No change
5
10 drops distilled water
No change
No change
6
10 drops reducing sugar solution
Blue
No change
7
10 drops starch solution
No change
Yellow-> Blue
8
Unknown
Blue-> Red
Brown
9
Unknown 2
Blue
Brown
4
10 drops glucose solution
Blue-> Brown
No change
Tube
Solution
Color
1
2 ml egg albumen
Green/yellow
2
2 ml honey
No change
3
2ml amino acid solution
Purple
4
2ml distilled water
No change
5
2ml protein solution
Purple
6
Unknown
Colorless
7
Unknown 2
Colorless