What makes bones strong?
Even though bones are very light, they are also very strong. However, how strong they are depends on how much of the mineral calcium carbonate they contain.
Eggs and bones contain calcium carbonate (CaCO3). When calcium carbonate and acetic acid combine, a chemical reaction takes place and carbon dioxide (CO2) is released. We can see this effect observing some bubbles in de solution.
But bones are made also of soft material called collagen. When bones are placed in the glass with acetic acid, this acid dissolve the calciu carbonate so that only collagen is left.
During foetal development, strong fibbers of collagen protein form a matrix for bones. The matrix is shaped like bones but is very flexible. The matrix solidifies by a process called calification. During this process, calcium phosphate or hydroxyapatite is deposited in the fibbers of collagen and gives the bones strenght and rigidity.
In this experiment we will make the bones lose their strength so that we can bend them without any kind of problem.
This happens when
we put the bones in acid, when we do that calcium carbonate becomes removed so we can see that the only substance that keeps left is collagen.
2. Objective
1) Identify mineral salts in organisms. 2) Understand the function of inorganic biomolecules in skeletal structures of organisms.
3. Hyphotesis
After one week of inmersing the bones in acid we can see that they become light so we can bend the without problems.
4. Material
-Some molluscs'shells (clams, mussels, etc.)
-Dried, cleaned chicken or lamb bones.
-Water
-Acetic Acid
-Tongs
-2x600 ml Beaker
-Clock glass
5. Process
Chicken or lambs bones:
-Carrefully we clean the bones of the chicken.
-Then we examine the flexibilty of the bone by trying to bend it with the fingers.
-In a beaker we make and acid acetic solution or add vinegar
-We put the bones inside the acid acetic solution we have made.
-After 24-28 hours we see what has happened to the bone. It's important to put a clock glass at the top of the beaker to protect the solution.
-Then we will remove the bones from the vinegar with a tong and soak them with water.
-We will write the results in our lab worksheet.
Mollusks shells:
-We take another beaker and make the same acid acetic solution.
-Once we have done it, we put inside some shells and make note of what is happening.
-We will write this observations in our lab worksheet.
6. Results
We decided to leave more than only 24-28 hours the bones inside the acid acetic solution because we saw that it was not enough time for make them lose their strongness, so after one week we tried to blend the bones one more time. The little bones had becomed light and flexibel (easy to blend) but the big ones continued being very strong.
The same happened to the mollusks shells.
7.Conclusion
Finally after all, my conclusion is that 24-28 hours is just a few time and not enough to see the results, and even one week is to short, so i think the best would have been to let the bones two weeks or nine days so that we could observe and verificate our hypotesis.
8. Questions
1. Write the reaction that takes place when the acid acetic reacts with the calcium carbonate.
CH3COOH + CACO3
2. What is happening when the shells are soaking of acetic acid? What are the bubbles that you can see?
They are releasing the CO3 and the bubbles are the reaction of it.
3. What is happening to the bone after some days of soaking it in acetic acid? Why is the bone flexible now?
It is becoming light and realising the CO3. The bone is flexible now because it has losed the calcium carbonate so that only collagen is left.
4. So, what is the function of the calcium carbonate in the skeletal structures?
The function is to give strongness to the skeletal structures
