Zusammenfassung der Ressource
1.2 - 1.3 Carbohydrates
- Monomer
- Polymer
- Polysaccharide
- Monosaccharide
- Glucose
- Hexose Sugar - C6H12O6
- Isomers
- a-glucose
- b-glucose
- Galactose
- Fructose
- Test For Reducing Sugars
- Reduction - A chemical
reaction involving the gain of
electrons
- Therefore a reducing
sugar = donates
electrons
- BENEDICTS TEST
- Alkaline solution of Copper (II)
Sulphate
- When HEATED with
a reducing sugar,
forms an insoluble RED
precipitate
- Disaccharides
- Glucose + Glucose = Maltose
- Glucose + Fructose = Sucrose
- Glucose + Galactose = Lactose
- Made in a CONDENSATION
REACTION
- Molecule of water MADE
- Glycosidic Bond
- Broken down in a
HYDROLYSIS REACTION into
original monosaccharides
- Molecule of WATER ADDED
- Test for Non-Reducing
Sugars
- Must be in
solution
- Add Benedict's regent and
heat
- No colour change
- Reducing sugar not present
- Add food sample to dilute HCl + heat
- This will hydrolyse any disaccharide
present into constituent
monosaccharides
- Add sodium hydrogencarbonate solution to neutralise acid
- Benedicts doesn't work in acidic conditions
- Test with pH paper
- Re-test with Benedict's
- Heat
- If a non-reducing sugar
present in original
sample, Benedict's will
turn orange/brown
- This is due to reducing monosaccharide's made
from non-reducing disaccharide