3.4 Testing For Carbohydrates Flashcards
What is the test for reducing sugars
Benedict’s year
What is a reduction reaction
A reaction involving the gain of electrons
What are reducing sugars
They can donate electrons or reduce another molecule or chemical
What is the chemical used in Benedict’s test
Benedict’s reagent (Alkaline solution of copper sulfate)
Describe how to carry out Benedict’s test
- Place the liquid sample to be tested in a boiling tube
- Add and equal volume of Benedict’s reagent
- Heat the mixture gently in a boiling water bath for 5 minutes
What colour will the solution be if there is no reducing sugar present
Blue
What colour will the solution be if there is a very low concentration of reducing sugar
Green
What colour will the solution be if there is a low concentration of reducing sugar present
Yellow
What colour will the solution be if there is a medium level of reducing sugars present
Orange
What colour will the solution be if there is a high level of reducing sugar present
Red
What is the most common non-reducing sugar
Sucrose
What is the test for starch
Iodine year
How is the doing test carried out
A few drops of iodine dissolved in potassium iodide solution are mixed with a sample
How do you tell if starch is present in a sample from the iodine test
If the colour changes from yellow/brown to purple/black starch is present
What are reagent strips
Test strips that can be used to test for the presence of reducing sugars
