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Bao Nguyen 09/17/14 Period 1 Ms.Ogo The Effect of Carbon Dioxide on Acidity of Saltwater On our planet, the Carbon cycle is a substantial geochemical cycle to the survival of all organisms. The cycle begins with phytoplankton on the ocean surface absorbing the carbon in the atmosphere along with sunlight to perform photosynthesis. When the organisms die or release waste, their matters sink to the bottom of the ocean which decompose into the Earth’s crust as fossil fuel and sedimentary rock. Eventually, extreme heat and pressure will cause the CO2 to return to the atmosphere as volcanic gas. In nature, it takes millions of years for the amount of fossil fuel we have already used to accumulate in the Earth’s crust. Industrial development leads to the excessive burning of fossil fuel, which incessantly contributes CO2 to the atmosphere. Although the ocean is a carbon sink, it can’t sequester the disproportionate CO2 in the air. Therefore, much of the CO2 enters the ocean and dissolves to form carbonic acid which causes ocean acidification. In this experiment, we aim to find out how CO2 affects the acidity of the ocean. We will model the ocean with a beaker filled with 100ml of saltwater added with a few drop of universal indicators to identify the pH. We will put the beaker on a white sheet of paper to make the pH color clearly visible. The beaker’s mouth will then be covered up with saran wraps. Lastly, we will poke a hole and insert a straw. A blower then begin blowing steadily through the straw for 2 minutes while the observer records the pH according to the color for every 30 seconds. When we blow into the water, we are actually breathing out CO2. When the CO2 enters water, it dissolves to form carbonic acid. We are measuring the pH by observing the universal indicator’s color and matching it to the pH scale. Measuring the pH will tells us how the CO2 affect the water’s acidity. I believe that the carbonic acid will disassociate in the water to form bicarbonate and hydrogen ion which will lower the pH of the water. If I blew into the saltwater, then its pH would decrease. There are a total of 4 protocol used in this experiment: control, A, B and C. The control protocol is exactly as previously mentioned in the procedure. For protocol A, we will use tap water instead of saltwater. For protocol B, the beaker will be placed on ice for 3 minutes and for protocol C, the beaker will rest on a heating plate for 3 minutes. The independent variable is the time since how long we blow determines how much CO2 is emitted. The type of solvent used, either saltwater or tap water is also an independent variable. Another independent variable is the temperature of the liquid. The dependent variable for all protocol will be the pH and the color of the water. The constant is the amount of solvent: 100ml. Data Table-Bubble Protocol Properties/Times 0:00 (0s) 0:30 (30s) 1:00 (60s) 1:30 (90s) 2:00 (120s) Control pH 7 7 6.5 6.5 6.5 Protocol Color Green Green Light Green Light Green Light Green Protocol pH 7.25 7 6.5 6 6 A Color Dark Green Green Light Green Yellow Yellow Protocol pH 7 6.5 6.5 6.5 6.5 B Color Green Light Green Light Green Light Green Light Green Protocol pH 7.25 7.25 7 7 6.5 C Color Dark Green Dark Green Green Green Light Green As I blew through the straw, more CO2 was being added to the water which dissolve to form carbonic acid. Carbonic acid disassociates and release bicarbonate ions and hydrogen ions into the water which lower the pH. The universal indicator shows that an increase in CO2 means a drop in the pH level. This shows that the carbonic acid released from CO2 in the atmosphere has a significant impact on the ocean’s acidity. Based on the experiment, the taps water affects the pH the most. The tap water is the only one out of all protocol that managed to reach 6 on the pH scale. My initial hypothesis was correct. The pH of the water decreased after being blown with the straw. In all protocol, the pH all decreased by at least .5 unit which shows that the blowing in the water with CO2 does in fact acidifies the water. From this experiment, I learned how something as simple as breathing could acidify water. This experiment seems to simulate the current predicament of the ocean and the possible outcome in the future. I realized that our current steadily increasing CO2 emission rate won’t take long before it makes the entire world’s ocean acidic, exactly as this experiment portrays. The Effect of Acidic Water on Sturdiness of Shells Marine organisms use calcium carbonate from mineral deposit as the basic building block of their shell and external skeleton. Regarding this experiment, if the shell was to submerge in the vinegar, then it would most likely corrode over time and become more fragile and brittle. Carbon dioxide as previously stated naturally come from volcano but human’s usage have led to excessive CO2 emission coming from mine, oil drilling, etc. I hypothesize that placing the clam in vinegar will make it handle less weight than the clam placed in saltwater. In this experiment, there are two essential protocols that uses two mussel clams. In the control protocol, we prepare a beaker with saltwater and in the experimental protocol, we prepare a beaker with vinegar. The two clams will immerse in the liquid at the same time for 30 minutes and will also be removed at the same time. In both protocol, the initial mass is the independent variable. Also an independent variable is the time and the solution: saltwater or vinegar. The constant is the 150ml solution of liquid. There are also two additional pre-treated clams that will simply be observed and tested for strength. The dependent variable for all clams is the final mass and the numbers of book they can lift without breaking. Data Table - Shell Protocol Property/Data Observation Initial Mass (grams) Final Mass (grams) Difference (grams) Endurance (Books) Control Seawater 90% White Grey color 3.1 3.1 0 17 Experimental Vinegar Lots of Bubble Broken Piece Distorted Color 2.8 2.7 0.2 10 High Exposure Small Scratch Brittle Washed Out 2.4084 1.7 0.7080 2 Low Exposure Less Brittle Broken Piece 2.2425 1.9 0.3425 4 As the experiment began, the shell immersed in vinegar produce immense bubbles which signify a reaction was occurring. Another sign of interaction between the vinegar and the shell was some small brittle piece on the shell was breaking off. Regarding nature, this experiment demonstrates the way that acid, represented by vinegar, corrodes the shell of organisms living in region with low pH. Lower pH means more acidic property which constitutes a more caustic environment for organisms, hence why their shell are so brittle. To these animals, having a proper shell protects them and allow for better survivability and adaptation. It definitely cost a lot energy for organisms to rebuild their shells, especially if the water is highly acidic which would corrode their shells even faster than they could fix it. Overall, this experiment confirmed my hypothesis that the clam treated in vinegar will be more fragile than the one treated in saltwater. It could only withstand the weight of 10 books as opposed to the control clam which handled the weight of 17 books. The vinegar clearly corroded the clam as the bubbles seem to show, consequently making it much weaker than the clam treated in saltwater. To conclude, this experiment verified that the carbonic acid from CO2 would destroy the calcium carbonate shell of marine organisms. This will hurt the primary production which will jeopardize the zooplankton which then affects the larger carnivorous animals, some also depending on shell to survive. In the end, ocean acidification would destroy ecosystem and the livelihood of our economy because it heavily depends on fishing.