Chemical analysis of calcium carbonate in bivalve shells

SCHOOL SAN fRANCISCO de PAULA iNTERNATIONAL BACCALAUREATE |
Chemical analysis of calcium carbonate in bivalve shells |
Viability study of bivalves rearing as carbon sinks |
|
Carmen Gajardo González |
20/02/2011 |

Number of words: 3 753 |

ABSTRACTThis extended essay investigates the percentage of calcium carbonate (CaCO3) present in four different species of bivalve which are common in the market: coquinas, clams, mussels and scallops. The method used to state the percentage is back-titration with hydrochloric acid, based o the use of an excess of acid that is subsequently titrated, so the amount that reacts could be calculated.

Whileinvestigating the age of the bivalve used, by examining the weight and size of our samples, the scope of research can be enhanced. It allows the comparison among different bivalve to know which one produces more calcium carbonate (CaCO3) in the same period of time. With the result an argument about the viability of bivalve rearing as carbon sinks could be established.

The conclusions reachedfrom the results are that scallops are the bivalves with a greater percentage of calcium carbonate (CaCO3) and the ones which grows their valves quicker. As an example, at British Columbia 278 tons of CO2 are absorbed by the production of scallops while 26,7 billion tons of CO2 are released to the atmosphere. This means that the production of scallops helps to decrease the amount of CO2 but willnot solve the whole problem.

ACKNOWLEDGEMENTS

Don Cesar, my supervisor, who has guided me and has been very patient.
To my family and friends that supported me when I was desperate.
To all teachers I have ever had, that have taught me the knowledge I needed to perform this extended essay.

INDEX

Page 2
3
3
4
5
6
7
7
8
8
9
9
9
10
11
11
12
14
18
23
24
27

*Index………………………………………………….………………………………………
* Background information………………………….…………………………………………
* Carbon dioxide in the atmosphere……………………………………………………
* Bivalves……………………………………………………………………………………
* Biological process of molluscs: shell production…………………………………………
* Calcium carbonate………………………………………………………………………
* Carbon dioxide……………………………………………………………………………
*Reactions…………………………………………………………………………………
* Principal section ……………………………………………………………………………….
* Materials…………………………………………………………………………………
* Variables…………………………………………………………………………………
* Proceeding conducted ……………………………………………………………………
* Back-titration of HCl……………………………………………………………………
* Titration of NaOH………………………………………………………………………
*Results……………………………………………………………………………………
* Titration of NaOH …………………………………………………………………
* Back-titration of HCl ……………………………………………………………………
* Growth rate………………………………………………………………………………
* Discussion……………………………………………………………………………………
* Conclusion………………………………………………………………………………………
* Bibliography…………………………………………………………………………………
* Appendix……………………………………………………………………………………….

BACKGROUND INFORMATION

CARBON DIOXIDE IN THEATMOSPHERE
Climate change is an important and present issue that affects all living beings. On the surface of this planet the climate changes in a cyclic way due to different circumstances that surround our habitat. One of these factors is the action of the Sun which makes life possible thanks to the energy it provides. However, this amount of energy is not always the same but varies along timewith solar activity, which also varies in a periodic way. Even more so, solar bursts are not constant or easily predictable. Other agents, like CO2, have only just recently started to increase in the atmosphere. Even though millions of years ago there was a great amount of this gas.

The so called greenhouse gas effect becomes more important when there is an...