Why is carbohydrates unknown

Approximately 1.00 ml of the known carbohydrate samples and the two unknown samples were transferred on separate labelled test tubes. About 1.00 ml of Molisch reagent then 1.00 ml of concentrated H2SO4 was added to each sample. The test was observed for any change and was recorded. With the use of new batch of samples each time, the remaining tests were conducted:

(a) Iodine test – 1.00 ml of iodine reagent was added to each sample.

(b) Benedict’s test – 1.00 ml of Benedict reagent was added to each sample then heated using water bath.

(c) Barfoed’s test – 1.00 ml of Barfoed’s reagent was added to each sample then heated using water bath.

(d) Seliwanoff’s test – 1.00 ml of Seliwanoff reagent was added to each sample then heated using water bath.

(e) 2,4-DNP test – 1.00 ml of 2,4-DNP was added to each sample then heated using water bath.

The identity of the unknown samples was determined by comparing it to the known carbohydrate samples.

explanation: grsaa