An Analysis of the Effects of Carbon Dioxide on the Dissolution of Calcium Carbonate in Marine Organisms

Overview

Objectives/Goals Ocean acidification is when carbon dioxide (CO2) is absorbed by seawater and chemical reactions occur, which reduce seawater pH, due to a higher concentration of hydrogen ions and therefore increases the carbonate ion concentration. This process is detrimental to the environment because many organisms are relying on the stable pH and a change would result in many organisms' inability to adapt to rapidly changing environment. Different sections of the ocean experience varying levels of temperature, subsequently varying levels of pH. If there is a constant rate of carbon dioxide dissolution that acidifies the solution, then the higher the temperature would result in a higher pH and lower calcium carbonate dissolution. Methods/Materials In the experiment, the masses of shells before and after being introduced to the acidic conditions were compared with each beaker experiencing the same rate of carbon dioxide dissolution. Temperature was the independent variable, as tropical, polar, and room conditions were measured, and the mass loss was the dependent variable. Surface of the shells were also observed to indicate other consequences of ocean acidification. Materials: Carbon dioxide tank, Aquarium mix, Beakers, Distilled water, Shells, Electronic Scale, Microscope, Dry bath, Water bath, pH meter, Stock pH solution (4.0 pH and 7.0 pH), Rod/ scrapper, Gloves, Rubber stoppers, Eye goggles Results The beakers that experienced a temperature of 22 degrees Celsius had a pH of 6.0, the beakers that experienced a temperature of 30 degrees Celsius had a pH of 6.45, and the beakers that experienced room temperature (25 C) had a pH of 6.3. Conclusions/Discussion As a result, the shells from the higher temperature underwent a lower amount of dissolution because the water molecules contain a higher amount of energy, through the form of heat, which creates an environment that is difficult for the carbon dioxide to dissolve into. Another factor that contributes to the effects of ocean acidifcation is the surface area to mass ratio, where the smaller the shell (the has a larger surface area) would lose the most mass because more of the shell is being exposed to the acidic water.

Competition history

• CSEF 2014 Chemistry · Entry S0603

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