FEHLING'S TEST: REDUCING SUGARS

INTRODUCTION: 
Fehling's solution is a chemical test used to differentitate between reducing and non-reducing sugars. This test is based on the reaction of a functional group of sugar molecules with Fehling's reagent.
Fehling's reagent has to separate solutions: Fehling's A and Fehling's B.
Fehling's A: is a blue aqueous solution of copper (II) sulphate.
Fehling's B: clear and colourless solution of potassium sodium tartrate and sodium hydroxide.

OBJECTIVES: 
- Identify reducing sugars.
- Comprehend redox reactions.
- Understand the relation between structure and reducing ability of some sugars.

PROCEDURE: 
1. Take 5 test tubes and label: G, M, S, L, ST
2. Put 2mL of distilled water inside each tube.
3. With different spatulas put a small amount of each sugar. Dissolve the sugar.
4. Add 2mL of Fehling's A solution and then Fehling's B.
5. Place each test-tube in a boiling water bath (250 mL beaker on a hotplate stirrer).
6. Observe what is happening.

Results: We can see that different test tubes have an orange colour.

Starch Hydrolysis: 
 7- Place 2mL of 1% starch in a test tube and add 0,5 mL of 3M HCL. Mix and place this mixture                in a boiling water bath for 10 minutes.
8- After 10 minutes, remove the tube from the water bath and let it cool. Neutralize this solution with 1M NaOH and mix well.
9- Transfer 10 drops of this solution to a small test tube.
10- Add 1mL of Fehling's A solution and 1mL of Feghling's B.
11- Heat for a few minutes in a boiling water bath.
12- Record your observations. Compare the results of this test with your results for                                       unhydrolyzed starch in the step 1 of this                                                                                                   experiment.

You can see that in the result the colour is blue/green that means that is neutralized.

SACCHARIDES PROPERTIES

Introduction: 
Saccharides are organic molecules consisting of C, H and O atoms. Usually the empirical formula is Cn H2n On. Are divided into three groups: Monosaccharides, Oligosaccharides, Polysaccharides.

Objectives: 
1- Identify different sugars from its properties.
2- Differentiate mono and disaccharides.
3- Understand the relation between structure and some proporties.

Procedure:
In the first part of the experiment we are going to test some physical properties of the saccharides you have in the lab: flavour, crystal structure and colour.
-FLAVOUR: put small amount of each saccharide in your hand and taste it, Is it sweet or not sweet?
-CRYSTALS: Observe a small amount of each saccharide on a clock glass under magnification.
-COLOUR: white, transparent or creamy.


TO TEST SOLUBILITY:
- Clean and dry 5 test tubes and label them: G, M, L, SU, S
-Put 5mL of water in each test tube.
-With the aid of a spatula, put a small amount of each saccharide inside the labelled test tube and test if they are soluble or insoluble.
- Observe is each saccharide forms a mixture called dissolution or a colloidal suspension.
- 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 ise to test a saccharide. The reaction is positive when iodine reacts by turning from yellow to a purple, dark-blue/black colour.

 
Results: We can see the different test tubes we put lugol's iodine , and one is in different colour, is the  the starch (positive).

Egg's shell

INTRODUCTION: 
Osmosis is a vital process in biological systems, as biological membranes are semipermeable. Water molecules travel through the plasma membrane in order to equilibrate the intra and extra cellular concentrations.

OBJECTIVES:
--> Know about the osmosis phenomena.
--> Understand the process of osmosis in plasmatic membranes.

PROCEDURE:
Egg: This experiment will be divided in two days.
FIRST DAY:
- Take a 600mL beaker and put inside the egg.
- Cover the egg with vinegar and make note of what's happening.

Once the egg's shell is removed and the egg is rinsed dry and clean, mesure and weigh the egg. Record the dimensions of each egg in a table.

- Clean the beaker and put the egg inside again.
- Cover it with distilled water. Make note of the volume of solution inside the beaker.

SECOND DAY: 
- Left the egg one day in the distilled water. After about a day, carefully remove the egg using a spoon. Rinse the egg with water and let it dry.

OBSERVATIONS:
We can see that the shell of the egg is more soft because of the water that are inside, if we touch the egg, the egg brekas because of the pressure of the water.

Results:
- Inside the egg we have hypertonic.
-Out the egg we have hypotonic (the water were inside the egg)

pH

Introduction: 
The pH is a mesure of the acidity or basicity of a solution. Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline. Pure water (distilled water) has a pH close to 7, neutral. (pH=-log [H+])

Objectives: 
1. Mesure different pH values of organic and inorganic solutions.
2. Prove different methods of measuring pH.

Procedure: 
1- Squeeze the lemon and tomato in two clock glasses.
2- Take a piece of indicator paper and place one end of it into the solution. Leave for at least 20 seconds.
3- Remove the indicator paper and compare its colour with the appropriate colour chart.
4- Repeat points 1 to 2 with as many others solutions as you are provided with,
5- Record your results in a result table in your worksheet.

How does concentration affect pH?
6- Prepare the test tube rack with 5 test tubes cleaned with distilled water. Mark the tubes with the labels: A, A1, A2, A3 and B.
7- Add 10 ml of Lemon juice to tubes A and B.
8- Take the A tube and put 5ml of its lemon juice to the test tube A1 (5ml of distilled water).
9- Take the A1 tube and put 2,5 ml of its lemon juice to tube A2 (7,5ml distilled water).
10- Take the A2 tube and put 1,2 ml of its lemon juice to tube A3 (8,7ml distilled water)
11- Add distilled water to each test tub until it has the same volume as test tube B (10 ml)
12- Calculate the concentration of each test tube with the formula.

Test          Volum of           Total           Concentration           pH
B              5 + 5                    10 ml           0,5                              2,70
A1            2,5+7,2                10 ml           0,25                            2,56
A2            1,2 +8,7               10 ml           0,13                            3,08
A3            1,2+8,8                10 ml           0,12                            3,08
A              10 ml                   10 ml           1                                 2,81

























QUESTIONS:
1. Which of the solutions gave and acid pH? Lemon, tomato, vinagre, coca-cola, HCL and wine.
2. Which of the solutions was alkaline? Na OH, soap solution.
3. Which of the solutions were neutral? Did you expect these results? Explain. Milk,  souy milk. Yes but the milk I though that was an alkaline.
4- How does a pH of 3 differ from PH of 4 in terms of H+ concentrations? HCL, H3 have more H+ than the H4, have 10 more H+.
5-
      a) Which is the dependent variable? Is the Ph
      b) Which is the independent variable? The lemon juice concentration.
      c) Which is the problem that we want to solve? Can the juice lemon concentration variate the          Ph3?
      d) Which is the control of the experiment? Is the B, have 100% lemon juice.
      e) Write the results and conclusions: Independent Variable
6- Which pH do you think that gastric juices might have? why? Do you think that intestinal pH has the same pH? why? Acid, because we need to combine with the food and remove. Fisrt we have basic acid but then change to acid.
7- Which pH do you think that blood might have? Why? Neutral (7,2)
8- What is acid rain? Which are the consequences in the ecosystems and how is its formation pattern? Is rain in Barcelona acid or alkaline? Destruction of forest, brake the rocks. We have acid or alkaline.

Osmosis

Introduction: 
Osmosis is the spontaneous movement of solvent molecules through a semipermeable membrane into a region of higher solute concentration (hypertonic), in the direction that tends to equalize the solute concentrations on the two sides. 

Objectives: 
- Know about the osmosis phenomena. 
- Understand the process of osmosis in plasmatic membranes.

Procedure: (Potato)
- Take the potato and cut it in three picies and put it every picie in a watch glass. 
- Take the spatula and make an small hole in the middle of each picie of potato. 

 1- Control of the experiment 
 2- Salt treatment (put salt inside the hole) and leave it. 
 3- Put distilled water treatment (leave it 20 min) 

Observations: 
In the first pass (control of the experiment) the potato is dry. 
In the second pass (salt treatment) the potato is with more water. 
In the third pass (distilled water) the potato absorbs the water. 


--> In the salt treatment we have the hypertonic medium 
--> In the distilled water we have the hypotonic medium