Chm 301 - Determining the Prence of Reducing Sugars

DETERMINING THE PRENCE OF REDUCING SUGARS

• APPARATUS AND MATERIAL :

Test tubes , test tube rack , marker pen , distilled water , glucose solution , sucrose   solution , starch solution , Benedict’s reagent , small ruler , labael stickes and boiling water bath.

• PROCEDURE :

1. From the bottom of 4 clean test tubes , 1 and 3 cm was marked . The top end of the test tube was labelled 1 , 2 , 3 , 4
2. Each test tube was filled to the 1 cm mark with one of the following :

• Distilled water ( test tube 1 )
• Glucose solution ( test tube 2 )
• Sucrose solution ( tets tube 3 )
• Starch solution ( test tube 4 )

1. Each test tube was added with 3 cm of Benedict’s reagent and the initial colour was recorded.
2. All the four test tube was placed in a boiling water bath for 3 minutes.
3. Then , all the test tubes was removed from the hot water bath with the test tube holder and placed in the test tube rack.The colour change of eacg test tube was recorded.Data was recorded in table.

• RESULT / DATA

POST LAB QUESTION :

1. Which test tube contain reducing sugars ?

• Test tube

1. Name the functional group present in carbohydrate molecule that can produce reation with Benedict’s reaction ?

• Carbonyl -  C=O

1. If onion juice mixed with Benedict’s reagent gives a mustard yellow colour , in what form is sugar stored in onions ?

• In form of reducing sugars , Fructose ( Mexju.2007.Science & mathematic – botany.14.August.2015.https://answers.yahoo.com/question/index?qid=20070924211906AA9RJw5 )

DETERMINING THE PRESENCE OF STARCH

•    MATERIAL / APPARATUS :

Test tubes , test tube rack , marker pen , microscope , distilled water , glucose solution , sucrose solution , white tile , fresh potato , razor blade , clean microscope slides , coverslip , label stickers , starch solution.

•   PROCEDURE :

1. From the bottom of 4 clean test tubes , 1 cm was marked . The top end of the test tube was labelled 1 , 2 , 3 , 4
2. Each test tube was filled with one of the following :

• Distilled water
• Glucose solution
• Sucrose solution
• Starch solution

1. 3 drops of iodine solution was added to each of the test tube and swirled to mixed.The colour of each test tube was recorded
2. The content of the test tube eas discarded and rinsed properly.Excess water was shake out from the test tubes.The next excersice used them.
3. A razor blade was used to cut small , thin slice of fresh potato .The potato slide should be transparent.
4. The potato slice was placed onto a clean microscope slide and wet mount was prepare.The potato slice was observed under low and high power.
5. The coverslip was removed and few drops of iodine solution was added.The coverslip was replaced  , the iodine to penetrate was waited for a few minute and the potato was observed again under a low and high power .The observation was draw.

• RESULT /DATA :

POST LAB QUESTION :

1. Draw the potato slide observed under a microscope

1. Does the blue black colour present in any of the carbohydrates solution beside starch ?

• No

1. Is the iodine test suitable to distinguish starch from sucrose ? Explain why ?

-

DETERMINING THE PRESENCE OF PROTIENS

• APPARATUS/MATERIAL :

Test tubes , test tube rack , small ruler , marker pen , distilled water , label stickers ,  honey solution , corn oil , egg white solution , 10% NaOH solution , 1% CuSO4

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