Lab 18: Gas Law Lab

   In the Gas Law Lab, we collected gas in a balloon that was given off by a powdered form of two Alka Seltzer tablets. We were able to do this because  the sodium bicarbonate (NaHCO3) and citric acid (C6H8O7) dissolved in the water (H20) and produced carbon dioxide (CO2). After that, we used the ideal gas law to determine the mass of the carbon dioxide (CO2).

Calculations


Analysis Questions

1. Discuss an area in this lab where experimental error may have occurred.
   Experimental error could have occurred when some water might have spilled out when my partner and I were measuring the volume un the graduated cylinder. The balloon is not a perfect sphere. The measurement of the circumference. could have been miscalculated.

2. Choose one error from above and discuss if it would make "n", the number of moles in carbon dioxide (CO2), too big or too small.
   The first error would make "n", the number of moles in carbon dioxide (CO2) too small because the spillage of water (H20) causes the volume to become lower than it actually is. The loss of volume is the loss of H20 molecules. The loss of H20 molecules results in a lower amount of carbon dioxide (CO2).

3. Filling the balloon with water may be one place where error could have occurred. Using the value for the circumference of the balloon in cm, calculate the volume of the balloon mathematically . Remember that the circumference of a sphere is 2𝝅r and volume is 4/3𝝅r3.

Circumference - 33 cm
Radius - 2𝝅r - 5.25 cm 
Volume - 4/3𝝅(5.25 cm)3 - 606 mL

4. Compare your answer to #3 to the volume obtained by filling the balloon with water . Is it close? Which do you feel is more accurate and why? Remember that 1cm3=1mL
   The two answers were not close. Measuring the volume with the graduated cylinder is more accurate because the balloon is not a perfect sphere. The circumference may not be accurate.

5. The ideal gas law technically applies to ideal gasses. Gibe two differences between a real gas and an ideal gas. 
   Ideal gasses are theoretical and fit into the equation PV = nRT and excerpt no force. Real gasses excerpt a small amount of force. Ideal gasses move at a constant motion. They do not collide with each other. Real gasses collide with each other and tend to speed up and slow down.

6. Would the CO2 you collected be considered ideal? Why or why not?
   No, the ideal CO2 exists in the perfect setting with the correct pressure, accurate measurements of the balloon's circumference, and no H20 volume lost.

Advanced Questions 

1. Using the information provided on the label, and stoichiometry, calculate the mass of CO2 that should be collected per tablet.


2. What is the percent yield for the CO2 collected in your sample? 

3. CO2 is water soluble. The solubility around room temperature is around 90 mL/ 100 mL of water. What effect does this have on your calculated "n" value?
   CO2 is water soluble, some of the gas would have dissolved in the water when we transferred all the water and Alka Seltzer powder into the balloon. This results in a lower "n" value and smaller circumference in the balloon.




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