How Much Co2 Lab Essay Example for Free

How Much Co2 Lab Essay Experimental: An Alka-Seltzer tablet was accurately weighed and recorded using a weighing boat and analytical balance. A fragmented piece between 0. 2100g and 0. 2800g was also weighed and recorded. 500mL of water was placed in a 600mL beaker. 80mL of water was then mixed with 20mL of 6M HCl in a 150mL beaker to create 1. 2M HCl. A 1. 5g piece of Alka-Seltzer tablet was then added to the HCl solution. After complete evolution of CO2, gravity filtration was used to catch all of the starch produced from the reaction. The buret was filled with the filtrated solution and the glass tube end of a rubber tube was inserted about 2 inches into the mouth of the buret. While keeping a finger over the buret mouth, the entire buret was quickly inverted and the tubing and mouth completely submerged into the water in the 600mL beaker. The buret was then clamped into place while double checking the buret mouth was under the water level and the rubber tubing was not pinched. The stopcock was then opened extremely slowly until the water level in the buret dropped close to the 50. 00mL mark. This level was then recorded. 25mL of the prepared HCl solution was added to a 125mL Erlenmeyer flask, along with a 0. 5-1. 0g piece of Alka-Seltzer tablet. After complete evolution of CO2, the neck of the flask and rubber stopper were completely dried. The tablet fragment earlier weighed (between 0. 21-0. 28g) was then added to the flask followed by immediate insertion of the stopper to ensure a tight seal. 5 minutes after the CO2 has been generated, the new water level of the buret was recorded, along with the distance in inches between the buret and beaker’s water levels. Lastly, the prevailing atmospheric pressure, temperature of the water, and approximate volume of the room was recorded. Results and Calculations Table 1 Experimental Values Experimental Values| Measurements| Current pressure of the room| 29. 3 in. Hg| Mass of entire tablet| 3. 2545 g| Mass of fragment| 0. 2524 g| Buret water level (start)| 45. 62 mL| Buret water level (end)| 7. 50 mL| Distance between buret and beaker water level| 3. 625 inches| Temperature of the water/room| 21. 8Â °C| Pressure of water at 21. 8Â °C| 19. 587 torr| Length, width, height of the room| 1463cm, 792cm, 366cm | Conversions: Temperature of the Room: 21. 8Â °C + 273. 15 = 294. 95K Volume of the room: (l? w? h) = (1463cm)(792cm)(366cm) = 424 x 108 cm3 = 424073L Pressure of room: 29. 3 in. Hg x 760 mmHg x 760 torr = 744. 3 torr 29. 92 in. Hg 760 mmHg 29. 3 in. Hg x 1 atm = 0. 97927 atm 29. 92 in. Hg Calculations: PÂ °atm = Patm – ( in. of H2O )( 1. 87 torr/in. of H2O ) = (744. 3 torr) – (3. 625 in. )(1. 87 torr/in. ) = 737. 521 torr PCO2 = PÂ °atm – PH2O = (737. 521 torr) – (19. 87 torr) = 717. 934 torr x 1 atm = 0. 94465 atm 760 torr VCO2 = 45. 62mL – 7. 50mL = 38. 12mL = 38. 12mL x (1L/1000mL) = 0. 03812 L NCO2 = PCO2VCO2/RT = ( 0. 94465atm )( 0. 03812L ) = 0. 0014873 mol CO2 ( 0. 08206 L? atm/mol? K )(294. 95 K) Moles of CO2 one tablet produces: (moles CO2) x (mass tablet/mass fragment) = (0. 0014873 mol CO2) x (3. 2545g / 0. 2524g) = 0. 019178 moles CO2 in tablet Moles of the room: Nroom = ProomV room/RT = (0. 9727atm)(424073L)/(0. 08206 L? atm/mol? K )(294. 95 K) = 17,042. 7 moles in room of tablets required to fill room: (moles of room) / (moles of CO2 per tablet) = (17,042. 7 moles) / (0. 019178 mol CO2) = 8. 887 x 105 tablets Mass of NaHCO3 needed to fill room with CO2: = 8. 887 x 105 tablets x 0. 019178 moles CO2 x 1 mol NaHCO3 x 84. 01g NaHCO3 1 tablet 1 mol CO2 1 mol NaHCO3 = 1. 432 x 106 g NaHCO3 Discussion In order to find the number of tablets needed to produce enough CO2 to fill the room, the ideal gas law was required first to solve for the number of moles of CO2 in one tablet and second the number of moles of the room. To use the ideal gas law, the atmospheric pressure was adjusted for due to the lower pressure in the buret when compared to the outer atmospheric pressure. This unequalization of pressures, although corrected, may still be slightly off, thus potentially causing later calculation error when using the ideal gas law to solve for the moles of CO2. Difficulties in the experiment arose when inverting the buret and completely submerging it into the beaker of water. This is a likely place for error because keeping a finger over the mouth of the buret and sealing the mouth tightly enough during the inverting process was very difficult. If too much of the solution inside the buret leaked out, one would not have enough volume to start with (before the CO2 evolution) and thus would have to remake the solution and repeat the process. Another potential source of error would be the measurement of the size of the room. With so many objects (lab tables, carts, ceiling structures) that also occupy the space, it was very difficult to determine an accurate volume of the room. Thus, the actual number of tablets required to fill the room might be a little bit less when the objects taking up space in the room are considered. Additionally, if the gravity filtration failed to filtrate all of the starch from the HCl solution, the leftover starch could potentially cause a problem in the reaction when the tablet fragment is added to the solution, thus providing more possible sources of error. Another minor source is the sensitive nature of the analytical balance, possibly leading to incorrect weight measurements of the tablet fragments. Another is general human error, such as reading the volume on the buret when determining the amount of CO2 evolved from the fragment. Conclusion In conclusion, the overall experiment proved to be successful; depending on the calculated size of the room, the number of Alka-Seltzer tablets required to produce enough CO2 gas to fill it was able to be determined. The mass of NaHCO3 needed to produce enough CO2 was also able to be calculated due to the fact that one mole of NaHCO3 is equal to one mole of CO2. Using the ideal gas law, Dalton’s law of partial pressure, stoichiometry, and conversions, a result was calculated, thus proving that future experiments dealing with the calculation of CO2 evolved from Alka-Seltzer by using an inverted buret can be done successfully.