To a solution or suspension of 0.2 g of unknown in 5 mL of water, add 5 mL of Fehling's solution and heat the mixture to boiling. Cool the solution.
Fehling's solution: Dissolve 17.32 g of hydrated copper sulfate in 200 mL of water and dilute to 250 mL. Dissolve 86.5 g of sodium potassium tartrate and 35 g of sodium hydroxide in 100 mL of water and dilute to 250 mL. Mix 2.5 mL of each solution immediately prior to use.
Precipitation of copper(I) oxide as a red, yellow, or yellowish-green solid is a positive test.
None.
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