1. Megan Logue

2.  Is a.1 M or a 1 M solution of sodium hydroxide more effective at extracting carbon dioxide from air?  Will carbon dioxide be removed from air more effectively by sodium hydroxide at 16°C or 32°C?

3.  The increasing amount of CO 2 in the Earth’s atmosphere has the potential to severely harm the environment and affect society.  The purpose of carbon capture is to remove CO 2 that would otherwise build up in the atmosphere.  One method of carbon capture is the implementation of artificial trees in the environment. ◦ An artificial tree operates by enabling air to filter through its structure and removing the air’s CO 2 with a sorbent material, such as sodium hydroxide, or NaOH.  The initial pH value of a solution of NaOH will decrease as it captures CO 2 from air.  This change in pH can be used to determine exactly how many molecules of CO 2 are extracted from air over a period of time.

4. http://a57.foxnews.com/images/590838/450/350/0_22_synthetic_trees_400.jpg

5.  A solution of NaOH and water can be used to extract CO 2 from air. The reaction between a solution of NaOH and CO 2 is as follows: ◦ CO 2 + H 2 O  H 2 CO 3 ◦ NaOH + H 2 CO 3  NaHCO 3 + H 2 O ◦ NaHCO 3 + NaOH  Na 2 CO 3 + H 2 O  Overall reaction: ◦ CO 2 + 2 NaOH = Na 2 CO 3 + H 2 O  This indicates that for every two moles of NaOH, one mole of CO 2 is extracted from air.

6.  As the concentration of the NaOH solution increases, the amount of CO 2 removed will increase as well.  Also, as the temperature of the system increases, the amount of CO 2 extracted from the air will also increase.

7.  2 L of 1 M solution of NaOH  2 250 mL Erlenmeyer flasks  2 100 mL graduated cylinders  2 aquarium pumps  2 stirring rods  Small weights  Water bath  Incubator  2 Vernier pH probes  2 Vernier temperature probes  Logger Pro Date Logger  Computer  Water  Paper towels  Safety gloves  Safety goggles  Safety apron  Calculator  Sink

8.  A.1 M solution of NaOH and a 1 M solution of NaOH were prepared in separate Erlenmeyer flasks. Both flasks were placed in the water bath set at 20°C.  A tube connected to an aquarium pump, a Vernier temperature probe, and a Vernier pH probe were placed in each flask.  The probes were set to collect samples at increments of 10 minutes over a time period of 24 hours with Logger Pro Data Logger.  After 24 hours, the collected data was recorded. The procedure at 20°C was repeated twice to perform a total of three trials.  Next, an incubator was set at 40°C. The.1 M and 1 M solutions of NaOH were placed in the incubator. A tube connected to an aquarium pump, a Vernier temperature probe, and a Vernier pH probe, were placed in each flask.  Once the temperature of each flask was stable at 40°C, the data collection was promptly started on Logger Pro Data Logger. After 24 hours, the collected data was recorded. The procedure at 40°C was repeated twice to perform a total of three trials.  After each trial was successfully completed, the changes in the pH of the solutions over time were calculated. Mathematical models were used to determine the amount of CO 2 molecules extracted from the air and removed by each solution.  The final results of the experiment were compared and analyzed.

9.  Independent Variables ◦ Temperature ◦ Concentration of NaOH solution  Dependent Variable ◦ Amount of CO 2 removed  Constants ◦ Erlenmeyer flasks, aquarium pumps, Vernier temperature probes, Vernier pH probes, stirring rods, small weights, Logger Pro Data Logger, computer

10. Average Decrease in pH at 16°CAverage Decrease in pH at 32°C

11.  The following calculation was used to determine the grams of CO 2 removed by each NaOH solution:  1 M at 16°C - Trial 3  pH = -log[H 3 O + ]  Initial pH: 13.02  [H 3 O + ] = 10 -13.02 = 9.54992586 x 10 -14  [OH - ] = 1.0 x 10 -14 / [ H 3 O + ] =.1047128548  End pH: 10.26  [H 3 O + ] = 10 -10.26 = 5.49540874 x 10 -11  [OH - ] = 1.0 x 10 -14 / [ H 3 O + ] = 1.8201385 x 10 -4  Initial [OH - ] – End [OH - ] = (5.49540874 x 10 -11 ) – (1.8201385 x 10 -4 )  Initial [OH - ] – End [OH - ] =.104530841 mol OH - removed  mol OH - removed / 2 =.104530841 / 2  =.0522654205 mol CO 2 removed  1 mol CO 2 = 44g  44g x mol CO 2 removed = 44 x.0522654205  = 2.299678502g CO 2 removed by 100 mL of.1 M NaOH at 16°C

13.  Stabilizing temperature  Limited materials  Evaporation of the NaOH solutions over the 24-hour time period  Time restrictions

14.  At 16°C, the.1 M NaOH solutions were more effective than the 1 M solutions.  At 32°C, the.1 M solutions produced similar results, but the 1 M solutions removed more molecules of CO 2. The final results suggested that the 1 M solutions were more effective at 32°C.  This refutes the hypothesis that the CO 2 extracted would increase as the concentration of the NaOH solution increased.  It was also hypothesized that the CO 2 extracted would increase as the temperature of the system increased. This was rejected for the.1 M solutions but accepted for the 1 M solutions.  Lower concentrations of NaOH are likely to be more effective at cooler temperatures, and greater concentrations of NaOH at warmer temperatures.  Further Research ◦ Cost-effectiveness, carbon disposal and storage, different concentrations of NaOH solutions

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