Lugol / Fehling

OBJECTIVES:

1. Identify different sugars
2. Understand the relation between structures

MATERIAL:

• 10 test tubs
• Beaker
• Spatula
• Bunsen burner
  
• 3 pipets
• Wire brush
• Distilled water
• Fehling A
• Fehling B
• Lugol
• Glucose
• Maltose
• Sucrose
• Lactose
• Starch

PROCEDURE: We put 5 test tubs in a test tube-rack, each one with each glucid, and we do the same with the other five test tubs in another test tube-rack. In one grup we will put Fehling and in the other Lugol.

Lugol: 

1. First put a little bit of each glucid in each test tube
2. Add 5ml of distilled water in each test tub
3. Observe what happens
4. Add 2 drops of Lugol
5. Observe the colour 

1. 
   

Fehling:

1.  Put a little bit of each glucid in each test tube
2. Add 2ml of distilled water
3. Add 2ml of Fehling A and 2ml of Fehling B
4. Put the test tube in a boiling water bath (beaker)
5. Observe the colour

RESULTS:

                     Glucose      Maltose      Sucrose      Lactose      Starch

Sweet            sweet          sweet           sweet         sweet          no sweet

Solubility      soluble        soluble        soluble       soluble        no soluble

Lugol            negative      negative       negative     negative       positive
Fehling         positive       positiva       negative     positive        negative

• In Lugol experiment: The Lugol reacts when in the substance there is starch, so when we do the experiment, only the solution with starch it's positive. The others are negative because don't have starch.

• In Fehling experiment: The Fehling reacts with the aldehydes, not with the ketones. So glucose, maltose, and lactose are positive in this experiments becouse are aldehyds. 

Osmosis

OBJECTIVE:
See what happens when we put NaCl and distilled water in a potato and when we put an egg in a vinegar solution and then in a distilled water solution.

MATERIAL:

• 1 egg
• Vinegar
• 1 potato
• Deistilled water  
• NaCl
• Spatula
• Beaker
• Knife

PROCEDURE:
Egg: This experiment is divided in two days.
1st Day:

1. Weight the egg
   
2. Take a 600mL beaker and put inside the egg
3. Cover the egg with vinegar
4. Once the egg's shell is removed, clean and dry the egg 
5. Weight the egg again and write down the number.
6. Put the egg in another beaker 
7. Cover it with distilled water. 

2nd Day:

1. Left the egg one day in the distilled water. After about a day rinse the egg with water and let it dry.
2. Weight again the egg and write it down.
3. Break the egg

Potato: 

1. Lay out three watch glass.
2. Slice the potato in three parts lengthwise. Each slice must be of 1,5cm thick.
   
3. Place each slice onto a watch glass and make a hole in the middle of each slice. The hole does not have to cross the slice.
4. In the first slice hole, don’t put anything. The second fill it with salt and the third with distilled water.
5. Left this preparation 30 minutes.

RESULTS:
Egg:
At the end of the experiment we saw that the distilled water entered into the egg through the sell. The egg increase his size and his weight and when we broke the egg there was lot of water. This is caused because of osmosis.

Potato: 
In the potato with distilled water, the water started to enter into the potato because the potato was hypotonic in relation to distilled water.
In the potato with NaCl, the water started to go out because the NaCl was Hypertonic in relation to potato.


QUESTIONS:
Egg questions:

1. What is happening when the shells are soaking of acetic acid? The shell is detached from the egg the CO2 is released.  
2. Write the results of the dimensions and weight of the egg before and after immersing it in distiller water. Write and draw a simple diagram of the water direction. Before immersing: 56'7g After immersing: 59'4g 
   

Potato questions:

1. Explain the results of this experiment. In the potato with NaCl, it appeared water and in the potato with distilled water, the quantity of water cut down.
2. Why have we left the first slice without any treatment (salt or distilled water)? For have a control.
3. Which are the dependent and independent variables? The dependent variable is the water that enter or leave into the potato and the independent variable is NaCl and distilled water.

General questions:

1. How can you explain (through osmosis) the ability of plant roots to draw water from the soil? The water has a lot of cohesion and the plants are an isotonic organism, so the roots can draw water from the soil.
3. What will it happen if a saltwater fish is placed in a freshwater (low concentration of salts) 
4. aquarium? The fish will absorb water and it will swell because of osmosis. 
Look the image you have below and explain what is happening to the erythrocytes in each situation. In the hypertonic solution the organism has more water than the solution, that has more salts and minerals, and the water leave the organism and it crease. In the isotonic solution the water that leaves the organism is the same quantity than the water that enter in the organism because the solution and the organism have the same quantity of minerals and salts. Finally in the hypertonic solution the organism has more salt and minerals and the water enter into the organism and it gets bigger.

pH

OBJECTIVES:
Know how much pH there's in a lemon and know how we indentify the pH of a lemon

MATERIAL:

• 4 tests tubes
• Water
• 1 lemon
• Beaker
• Destiller water
• Forceps

PROCEDURE: Put in different tubs this quantity of lemon and water

Tests tubes      H2O     Lemon    pH

       1                 1ml   +   5ml         ?

       2                 2ml   +   4ml         ?

       3                 3ml   +   3ml         ?

       4                 4ml   +   2ml         ?

RESULTS:
All the tubs with different solutions had the same quantity of pH, 3.

Tests tubes      H2O     Lemon    pH

       1                 1ml   +   5ml         3

       2                 2ml   +   4ml         3

       3                 3ml   +   3ml         3

       4                 4ml   +   2ml         3

QUESTIONS:

1. Which is the dependent variable? The dependent variable is the pH.
2. Which is the independent variable? The independent variable is the lemon.
3. Which is the control? The control are the tubs that only contains water ans lemon.
4. Which pH do you think that in blood? And in gastric juice? The pH of the blood is neutral because if it was acid the cells will die. And the pH of gastric juice is acid because it has to dissolve the aliments.

       

Mineral Salts in Organisms

OBJECTIVE:
We want to see how much CaCO3 there is in the bones and in the molusc's shells.

MATERIAL:

• Acid acetic 
• Chicken bones
• Mollusc's shells
• Baker
• Tongs
  

PROCEDURE:
Bones:

1. Carefully clean and cut ad much of the meat away from the chicken thin bone as possible.
2. Examine the flexibility of the bone by trying to bend it with yours fingers.
3. Take a beaker and make and add vinegar.
4. Take the bones and drop them in the vinegar.
5. Leave it 24 hours and see what happens to the bone.
6. Remove the bones from the vinegar with a tong and soak them with water.
7. Write the results in the blog.

Mollusks shells:

1. Take another beaker and make the same vinegar solution.
2. Put inside some shells. 
3. Write the observations in your blog.

RESULTS:
The bones became flexible but not a lot because they have other substances. The mollusks shells became flexibles and someones desintegrated.

QUESTIONS:

1. Write the reaction that takes place when the acid acetic reacts with the calcium carbonate. 
   
   
   
2. What is happening when the shells are soaking of acetic acid? What are the bubbles that you can see? When the shells are soaking of acetic acid or vinegar there's reaction with the CaCO3 and the vinegar. The bubbles I can see are carbon dioxide.
3. What is happening to the bone after some days of soaking it in acetic acid? Why is the bone flexible now? The bone become flexible. Is flexible now because the CaCO3 is disolved and now the bone only have colagen.
4. So, what is the function of the calcium carbonate in the skeletal structures? The function of the calcium carbonate in the skeletal structures is make the structures strong
5. Increases in carbon dioxide to the atmosphere from the burning fossil fuels and deforestation threaten to change the chemistry of the seas. Evidence suggests that this increase in atmospheric carbon dioxide is lowering the pH of the oceans in a process called ocean acidification. How can acidification efects corals reefs? The acidification make the corals lose the CO2