If the patient has diabetes, glucose will be present in the urine. Work backwards: assume the patient has diabetes. If a reducing sugar is not present, the Benedict's solution will not change colour and will remain blue.īenedict's solution produced a brick-red precipitate which indicates the presence of a reducing agent such as a reducing sugar which could be glucose. (2) What is the relationship between what you know and what you need to find out? Glucose is a reducing sugar.īenedict's solution will produce a brick-red precipitate of Cu 2O in the presence of a reducing sugar. (b) Benedict's solution changed colour when added to the urine sample. (1) What information (data) have you been given in the question? (a) Glucose is present in the urine of a diabetic. What is the question asking you to do? Determine whether the patient could have diabetes. If you add one of the mild oxidising agents above to sucrose, there will be NO reaction, no colour change. Of the disaccharides, maltose and lactose are reducing sugars, but sucrose is NOT. If one of the mild oxidising reagents above is added to a monosaccharide aldose sugar you expect to see the relevant colour change.Īlthough fructose is a ketose sugar containing the ketone functional group, it is also a reducing sugar. We expect aldose sugars to be reducing sugars. In general, an aldehyde functional group is easily oxidised to a carboxyl functional group.
Reducing sugar is oxidised to carboxylate Since the oxidation state of Cu has decreased, the copper "atoms" have gained an electron, that is the copper "atoms" have been reduced.Ĭolour After Reaction with a Reducing Sugar In order to test whether a sugar can be oxidised or not, we need to add a species that can undergo reduction.Ī species that undergoes reduction is known as an oxidising agent, or oxidant, because it causes the other species (the sugar) to be oxidised.īlue solutions of copper ions, Cu 2+, are popular oxidising agents for sugars because they produce an insoluble Cu 2O precipitate which is a brick-red colour that is easy to see. Therefore a sugar that is oxidised must be causing another species to be reduced, so the sugar is a reducing agent (or reductant), or a reducing sugar.Ī sugar that can NOT be oxidised is known as a non-reducing sugar. In the process, the reducing agent is itself oxidised. If a carbonyl group can undergo mild oxidation it will produce a carboxylate ion (COO -).Ī sugar that can be oxidised is known as a reducing sugar.Ī reducing agent is a species that causes a different species to be reduced. Play the game now! Testing for the Presence of a Reducing SugarĪnother to classify sugars is on the basis of a chemical reaction, that is, on whether the sugar can be oxidised or not. (" ket" from ketone + "ose" for a reducing sugar.) Sugars that are ketones are known as ketoses. (" ald" from aldehyde + "ose" for a reducing sugar.) Monosaccharides that are aldehydes are known as aldoses.
#Pour some sugar on may no words free
No ads = no money for us = no free stuff for you! Structure and Classification of Monosaccharides: Aldoses and Ketoses Common oxidising agents used to test for the presence of a reducing sugar are:.The disaccharide sucrose is a non-reducing sugar.The disaccharides maltose and lactose are reducing sugars.All common monosaccharides are reducing sugars.A non-reducing sugar is a sugar that is NOT oxidised by mild oxidising agents.Sugars that can be oxidised by mild oxidising agents are called reducing sugars.In the closed-ring structure (cyclic structure), the carbonyl carbon is the one which is attached to the O of the ring and an OH group.In the open-chain form, the carbon atom that contains the C=O bond is called the carbonyl carbon.Sugars exist in solution as an equilibrium mixture of open-chain and closed-ring structures.Ĭlosed-ring structures are also known as cyclic structures.You need to become an AUS-e-TUTE Member! Reducing and Non-reducing Sugars Chemistry Tutorial Key Concepts Want chemistry games, drills, tests and more? Reducing and Non-reducing Sugars Chemistry Tutorial More Free Tutorials Become a Member Members Log‐in Contact Us
0 kommentar(er)
