Date post: | 05-Jan-2016 |
Category: |
Documents |
Upload: | bartholomew-hicks |
View: | 213 times |
Download: | 1 times |
The Effects of Acids on Seashell Corrosion
Carla GiannandreaAcademy of Notre Dame de Namur
Question
What will happen to the percent change in the mass of seashells when soaked in different acid solutions?
Background Information
• Earth’s oceans absorb the carbon dioxide in the air emitted by humans.
• The acidity level of water has risen from 8.2 to 8.1
• Acids are considered either strong or weak• There are three types of acids, monoprotic,
diprotic, and tripotic acids.• Seashells are comprised of three shell layers...
• Proteinaceous periosteum• Prismatic layer• Inner pearly layer of nacre
Hypothesis
The percent change of the mass of seashells will increase as the pH levels of the different acid solutions decrease
Materials
• 72 seashells• Balance• 36 large glass jars• pH meter• HCl (Hydrochloric Acid)
• H2SO4 (Sulfuric Acid)
• HNO3 (Nitric Acid)
• Distilled water
http://sciencetools-w310.wikispaces.com/file/view/1w310_005.JPG/125401779/1w310_005.JPG
Procedure
• Three different solutions of 500 mLs of HCl were made, each with different pH level
• Each solution was then put into a different jar.
• Steps one and two were done with acids HNO3 and H2SO4 as well.
• Distilled Water was put into nine different jars.• The seashells were massed and put into the
solutions for seven days.• When taken out, they were massed again and the
percent change in mass was found in each seashell.
• Independent Variables• Different types of acids• Different pH levels of acids
• Dependent Variables• Percent change in the mass of the seashells
• Control• Seashells soaked only in distilled water
• Constants• Approximately same sized seashells• Same amount of solution in each jar• Soaked for the same amount of time• Maintained under tha same conditions
Average Percent Decrease in Mass of Seashells Soaked in HCl Solution
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
Distilled Water HCl ph 5 HCl ph 4 HCl ph 3
Avg. Percent Change in Mass
Average Percent Decrease in Mass of Seashells Soaked in HNO3 Solution
0
0.1
0.2
0.3
0.4
0.5
0.6
Distilled Water HNO3 ph 5 HNO3 ph 4 HNO3 ph 3
Average Percent Change in Mass
Average Percent Decrease in Mass of Seashells in H2SO4 Solution
0
0.1
0.2
0.3
0.4
0.5
0.6
Distilled Water H2SO4 ph 5 H2SO4 ph 4 H2SO4 ph 3
Average Percent Change in Mass
T-Test P. Value
Distilled Water to HCl ph 5 0.043
Distilled Water to HCl ph 4 0.043
Distilled Water to HCl ph 30.681
Distilled Water to HNO3 ph 5 0.168
Distilled Water to HNO3 ph 4 0.765
Distilled Water to HNO3 ph 3 0.938
Distilled Water to H2SO4 ph 5 0.745
Distilled Water to H2SO4 ph 4 0.978
Distilled Water to H2SO4 ph 3 0.191
Discussion and Analysis
Conclusion• The results of this experiments
concluded that short term exposure to acid solutions does not affect the mass of seashells.
• A source of error could have been inaccurate readings of the pH meter when making the solutions.
Further Research
• Testing change in softness of the seashells instead of change in mass
• Using different types of seashells• Using a control with pH 8.1 (the pH
level of the ocean)• Using a control of salt water
instead of distilled water
ReferencesAcid. (1990). In S. P. Elliot, M. Goldstein, & M. Upshall (Eds.), Webster’s New World Encyclopedia (9th
ed., p. 7). United States of America: Prentice Hall. (Original work published 1948)
Acid and Base Chemistry. (n.d.). Retrieved October 6, 2002, from Shoder website: http://www.shodor.org/unchem/basic/lab/
Acids. (n.d.). Retrieved October 6, 2010, from http://hyperphysics.phy-astr.gsu.edu/hbasic/chemical/acid.html
Bivalve Shell. (n.d.). Retrieved from http://en.wikipedia.org//_shell
Brewer, P. G., & Barry, J. (2008, October 7). Rising Acidity in the Ocean: The Other CO2 Problem. Scientific American. Retrieved from http://www.scientificamerican.com/.cfm?id=rising-acidity-in-the-ocean&page=2
Carpi, A. (n.d.). Acids and Bases. Retrieved 2003, from http://www.visionlearning.com/library/module_viewer.php?mid=58
Chemistry (A. C. Wilbraham, D. D. Staley, M. S. Matta, & E. L. Waterman, Trans., pp. 271,589-591, 600-607). (2008). Boston, Massachusetts: Pearson Prentice Hall.
References (continued)Hardt, M. J., & Safina, C. (2010, August). Threatening Ocean Life from the Inside Out. Scientific
American, 66-73.
Horne, F. (2006, October 23). How are seashells created? Or any other shell, such as a snail’s or a turtle’s? [Special section]. Scientific American. Retrieved from http://www.scientificamerican.com/.cfm?id=how-are-seashells-created
pH Indicator. (n.d.). Retrieved from http://en.wikipedia.org//_indicator
Seashells. (n.d.). Retrieved October 4, 2010, from Wikipedia website: http://en.wikipedia.org/wiki/Seashell
Where do Seashells come from? (n.d.). Retrieved from http://www.seashellsandsuch.com/articles/wherecomefrom.php