Practicals Flashcards
What is the result for the test for lipids?
Positive: A white emulsion forms.
What is the test for lipids?
Dissolve in ethanol, shake.
Add distilled water, shake.
What is an emulsion?
A substance with no solids.
What is the test for starch?
Add a drop of iodine.
What is the result for the test for starch?
Positive: Turns blue/black.
Negative: Remains orange.
What is the test for proteins?
Add a drop of biuret solution.
What is the result for the test for proteins?
Positive: Turns lilac purple.
Negative: Remains blue.
What is the test for reducing sugars?
Add benedicts reagent and heat.
What is the result for the test for reducing sugars?
Positive: Turns green, yellow, orange, brick red.
Negative: Remains blue.
What is the test for non-reducing sugars?
Add acid and bring to boiling for 2 mins so acid hydrolysis occurs. Cool in a beaker and add alkali to neutralise. Carry out benedicts test.
Why is acid hydrolysis required for non-reducing sugars?
Breaks sucrose into glucose and fructose.
