Detection of unknown sugar sample solution
Detection of unknown sugar sample solution General Test:1 1.Benedict's Test Experiment 3ml sample solution and 2-3 ml Benedict's qualitative reagent are mixed in a dry clean test tube and boiled for 5 minutes. Observation The mixture solution turns green, yellow and finally red. Inference The supplied sample is of reducing sugar. The red ppt. is Cu2O (I). Reactions : Reducing sugar+alkali—>Enediols Enediols+2 Cu2+---> 2Cu+ + acidic sugar 2Cu+ + 2OH– —-> 2CuOH 2CuOH +Heat —> Cu2O (red ppt) +H2 O General Test 2.Barfoed's Test Experiment 1 ml (5 drops) sample solution and 3 ml Barfoed's reagent ( a soln of cupric acetate and acetic acid) are mixed in a test tube and boiled in a boiling water bath for 3 minutes. Observation A reddish ppt.is formed. Inference The reducing sugar is a monosaccharide since ppt is formed within 3 minutes. Reaction : R–CHO + 2 Cu2+ +2H2O—-> R–COOH + Cu2O + 4H+ Confirmatory Tests : 1.Moore's Test Ex
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