carbohydrates

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CARBOHYDRATES ­ MONOSACCHARIDES
- Carbohydrates are polymers, made up of monomers.
- The basic monomers are known as saccharides. A single monomer is a
monosaccharide and a double is a disaccharide.
- Monosaccharieds are sweet soluble substances with the general formula (CHO)n
where n can be any number from 3 ­ 7…read more

GLUCOSE
- An example of a monosaccharide is glucose, which is a hexase sugar ­
C6H12O6.…read more

TEST FOR REDUCING SUGARS
- All monosaccharide's and some disaccharides are reducing sugars.
- Reduction is a chemical reaction involving the gain of electrons. A reducing
sugar is therefore a sugar which can donate electrons or reduce another
sugar.
- The test for reducing sugars is the Benedict's test:
- 1. Add 2 cm3 of the food sample being tested to a test tube.
- 2. Add an equal volume of Benedict's reagent.
- 3. Heat the mixture in a gently boiling water bath for 5 mins.
- 4. If the mixture turns brick red then it is a reducing sugar.
The test is semi quantitative because it is based on differences in colour.…read more

DISACCHARIDES
Glucose and Glucose makes maltose.
Glucose and fructose makes sucrose.
Glucose and Galactose make lactose.
The molecules join in a condensation reaction. A molecule of water is removed
and the bond formed is a glycosidic bond.…read more

TEST FOR REDUCING SUGARS
Some disaccharides such as sucrose are non-reducing sugars.
To test them they must first be broken down into the monosaccharide's, this is
done by adding hydrochloric acid and heating in a boiling water bath.
Then Hydrogen carbonate solution is added to neutralise it.
Then it can be tested with Benedicts reagent- the reducing sugar test.…read more