Outline7 marksChallenge
A student wants to test an unknown solution for the presence of protein using the biuret test. They set up three test tubes:
- Tube A: 2 cm³ of distilled water
- Tube B: 2 cm³ of a 1% egg albumen solution (known protein)
- Tube C: 2 cm³ of the unknown solution
They add 2 cm³ of biuret reagent to each tube, mix, and observe after 5 minutes. Tube A remains blue, Tube B turns purple, and Tube C turns a very faint purple.
Outline the purpose of tubes A and B, the procedure for the biuret test, and how the student should interpret the result for tube C.