Verification of reducing sugar with Fehling's solution


Chemicals needed

Fehling's solution    GSATZEND.gif (935 Byte) C    R 35    S (2)-26-27-37/39

glucose


Equipment needed

test tube
burner (preferably alcohol)


Test procedure


Disposal


Elucidation

Fehling's solution is alkaline and contains Cu(II). This does not precipitate inasmuch as it is complexed with tartrate. The aldehyde group of glucose is oxidized to carboxylic acid, whereby Cu(II) is reduced to Cu(I). This is precipitated as copper(I)-hydroxide. In general, one can verify with Fehling's solution reducing compounds, especially aldehyde.


Photos

DSCN0439.JPG (191338 Byte)

Reduction of Fehling's solution with glucose


Literature

based on a school experiment