1.5 Saccharides properties

Introduction 
Saccharides are organic molecules consisting of C, H and O atoms; and the empirical formula is Cn H2n On.

Are divided into thte goups:
-Monosaccharides: formed by a linear carbon chain, the oligo and polysaccharides are formed by these.
They have a one funcional group: cetone (C=O) or aldehyde (COH).
Pentoses and hexoses in dissolution can cyclic forming shapes called furanoses and pyranosres.
-Oligosaccharides: small polymer containing between 2 and 10 monosaccharides.
-Polysaccharides: big polymers with more than 10 monosaccharides.

These molecules perform numerous roles in living organisms like storage if energy, structural components .

Saccharides yield 4,2 Kcal/g. They are a common source of eneregy in living organisms.


Materials
-Test tube rack
-10 mL pipet
-Distilled water
-5 test tube
-1 dropper
-5 spatula
-Lactose
-Maltose
-Glucose
-Sucrose
-Starch
-Lugol's iodine


Objectives
1.Identify differents sugars from it's properties.
2.Differentiate monoand disaccharides.
3.Understand the relation bettween structure and some properties.


Procedure
1.In the firspartof the experiment we are going to test some physcal properties of the saccharides you have in the lab: flavour, crysta structure and colour. How?
          a. Flavour:Put a small amount of each saccharides in your hand and test it! Is it sweet            or not sweet?
          b. Crystals: Observe a small amount of each saccharide on a clock glass under                      magnification.
          c. Colour: White, transparent or creamy.

The propierties of 5 saccharides:



To test solubility:
2. Clean and dry 5 test tubes and label them "G, M, L, SU, S" 
3. Put 5 mL of water in each test tube.
4. With the aid of a spatula, put a small amount of each saccharide inside the labelles test tube and test if they are soluble or insoluble.
5. Observe if each saccharide forms a mixture called dissolution or a colloidal suspension.

Lugol's iodine Test:
6. Finally, add 2 drops of Lugol's iodine to each test tube and test if the reaction is positive or negative. Lugol's is a solution of elemental iodine (I) and potassium iodine (KI) in water that is use to test a saccharide. The reaction is positive when iodine reacts by turning from yellow to a purple, dark-blue/dark colour.

Finally we are going to test if some foods contain starch. Try with potato!
1. Add 2 or 3 drops of Lugol's solution to one piece of potato observe what is happening.


Observations
We can see that different test tube we put lugol's iodine, and one is in the different colour, is ti the strach (positive).
Questions
1.Write the empirical formula of each saccharide thet you have use. Show structures ofthe five saccharides.Classify each one in one group: mono, oligo, or polysaccharide.
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2.Which of the monosaccharide are aldoses and wich are cetoses?
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3.Which bond links monosaccharide?
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4.Which saccharide/s is/are sweet? Is this property related to the structure of the molecules?
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5.Whichsaccharide/s is/are insoluble? Is this property related to the structure of the molecules?
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6.Which saccharide has reacted whith Lugol's iodine solution?
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7.Which kind of food contains starch?
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8.Calculate the energy from the nutrition facts label from a cereals:
   a.Calculate the energy that comes from the saccharides.
   b.Which % of the total energy comes from the saccharides?