The Effects of Temperature on Limestone's Ability to Decrease Ocean Acidification
Annie Guan
Britannia Secondary
Floor Location : M 039 V

The purpose of this experiment is to determine the effects of temperature on limestone's ability to decrease ocean acidification. It was hypothesized that if increasing the temperature quickens reaction rates, then limestone will dissociate in a shorter span of time, allowing liberated carbonate ions to take acidic hydrogen ions and decrease water acidity. It was found that the dissociation of limestone and the reaction between liberated carbonate and hydrogen ions was quickest at higher temperatures. In this experimentation, the Kinetic Molecular Theory and Le Chatelier's Principle played significant roles in the results. The Kinetic Molecular Theory contributed to the success of the heated samples, but is also the reason why the cooled samples failed. According to the Theory, a rise in temperature would have increased the movement of particles, allowing limestone calcium carbonate to dissociate in a shorter span of time. On the other hand, a decrease in temperature slows down the movement of particles, making it harder for limestone calcium carbonate to dissociate. The room temperature samples were not affected by temperature, the speed of pH increase was between the heated and cooled samples. The crushed limestone had a greater surface area, making it easier for the liberated carbonate and hydrogen ions to react with each other. Although a heated environment helped speed the process of limestone in ocean water, the ending pH was not ideal like the other temperature samples. For both the room and cold temperature samples, the ending pH was around 7 which was the ideal pH, but the ending pH for heated samples were around 6.3. According to Le Chatelier's Principle, an increase in temperature would have shifted the equilibrium of water, causing it to produce more acidic hydrogen ions and hydroxide ions. The pH probe read the water as more acidic due to the excess amount of hydrogen ions. The results of this experiment can be utilized to decide when and where the implementation of limestone in acidic oceanic water is most effective, and it is when the ocean is warmer than usual. The slight increase in temperature will speed up the reaction between carbonate and hydrogen ions but will not be high enough to shift the equilibrium of water.