Chemistry Paper 3B WASSCE (SC), 2018

Question 3B

 

 

Observation

 

majority of the candidates applied theoretical knowledge by writing addition of iodine solution to starch. They assumed that the sample was starch.

The expected answer include:

To a portion of the sample

(a) Add Fehlings solution/Benedict solution/Tollen’s reagent and heat  formation of brick red precipitate indicates the presence of glucose.
No visible reaction indicates sucrose/starch.

(b) To another portion of the sample add few drops of iodine solution.  Formation of blue black colouration indicates the presence of starch .No visible reaction indicates glucose/sucrose .