Mineral Salts in Organisms

Introduction: 

- In this experiment we work with bones and shells. The bones are very hard and their hardness depends on the amount of calcium carbonate (CaCO3 ) in them . What we do in this experiment is that the bone are more flexiblity. And the same with the shells.

Materials:

- Some mollusk shells (clambs, ...)
- Dry cleaned chicken or lamb bones
- Water
- Acetic acid
- Tweezers
- 2 x 600 ml Glass
- Crystal Clock

Objectives:

1. Identify minerals salts in organisms.
2. Understand the function of inorganic biomolecules in skeletal structures of organisms.

Procedure: 

Bones:

- Separate the chicken-bone and clean it carefully.

- Examine the flexibility of the bone.

- Take a beaker and put the acid acetic solution or add vinegar (400mL) and water (200mL) inside of it. Later we put the bone inside the beaker.

- 24 hours later we returned to see the results of the bone.

Observations of bones: 

The bone is more flexible because it is contact with the acetic acid and the vinegar, and lose his hardness.

Shells: 
- Took a different beaker and put water and calcium carbonate.
-Inside the beaker put the shells that the teacher gave us.


Obervations of the shells: 
-In the change of class we observed that the shells were smaller and had holes.
-Later, we saw a lot of bubbles in the beaker.
 


QUESTIONS: 
1. Write the reaction that takes place when the acid acetic reacts with the calcium carbonate.
    Bubbles
2. What is happening the shells are soaking of acetic acid? What are the bubbles you can see?
    The bubbles 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 is more flexible
4. So, what is the function of the calium carbonate in the skeletal structures?
    Rigidity.
5. Increases in carbon dioxide to the atmosphere from the burning fossil 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 affects corals reefs?
    The reefs coral will be dissolve because the pH will be reduce of the corals.