Unknown Carbohydrates Lab Report

Sophie Arnott

Title
Identification of Unknown Carbohydrates Using Various Biochemical Tests
Aim
To identify various unknown carbohydrates by subjecting them to a series of biochemical tests.
Introduction

Materials
Lab coat
Safety goggles
Gloves
6 solid carbohydrates- Glucose, Maltose, Fructose, Starch, Sucrose, Cellulose
Permanent marker
Deionised water
Benedict’s solution
Barfoed’s reagent
Diastix strips
Iodine
Boiled water
Large beaker
12 test tubes
Dimple tray
Spatula
Dropper pipette

Experimental Method
Lab coats, safety goggles, and gloves were worn.
Materials were collected and laid out on the bench.
The first test carried out was solubility in water. Using a spatula, a small amount of each solid carbohydrate was added

Approximately 3ml of each solution produced in the previous test was inserted into a test tube using a dropper pipette. 4 drops of Benedict’s solution was added to each test tube and mixed well. Then each test tube was placed in a beaker containing boiling water. Any colour changes seen within 5 minutes were noted in the results table.
The third test carried out was Barfoed’s test. Approximately 3ml of each carbohydrate solution was inserted into a test tube using a dropper pipette. 4 drops of Barfoed’s solution was added to each test tube and mixed well. Then each test tube was placed in a beaker containing boiling water. Any colour changes observed were noted in the results

Discussion
By reviewing the results table, all 6 types of carbohydrates can be determined.
In the iodine test, a colour change was observed in carbohydrate F, but a more noticeable colour change was observed in carbohydrate E. Starch turns a dark blue-black colour in the presence of iodine, meaning carbohydrate E must be starch.
In the clinistix test, solution A caused the clinistix strip to turn green-brown, meaning carbohydrate A must be glucose.
The Barfoed’s solution test was carried out to determine if the carbohydrate was a reducing monosaccharide, such as glucose and fructose. After carrying out this test, carbohydrate B turned a brick-red colour, meaning it must be either glucose or fructose. However, carbohydrate A was already determined to be glucose using the iodine test, meaning carbohydrate B must be