Week 5 - Lab Discussion complete solutions correct answers writing

Week 5 - Lab Discussion complete solutions correct answers writing

1.    Briefly explain the purpose of each lab in your own words so that someone who has never performed the lab can understand the importance of it. Then summarize the team discussion on individual results.

·         Team Member A: The purpose of the lab was to verify Boyle's Law which states that pressure and volume of a gas have an inverse relationship when kept at a constant temperature.  Pressure is measured in a syringe filled with gas and observations are made when pressure is increased resulting in changes in volume.

·         Team Member B: I agree with you, Team Member A, on the purpose of this lab, which it is to verify Boyle's law.  Boyle's law describes how the pressure of a gas tends to increase as the volume of a gas decreases at a constant temperature.

·         Team Member C: The purpose of the lab was to examine Boyles Law. We did this by measuring the pressure of a syringe filled with room air. We added pressure in the form of books to the syringe to measure the resulting volume change in the syringe.

2.    • Discuss and compare your responses to the end-of-lab questions.

·         Team Member B: My results are a bit different from yours, Team Member A.  I think I was confused on the types of graphs I needed to do.  I only have one kind of graph and you have two.  Also on the first three rows my volume was the same even though my pressure was increasing.   I started with zero books or pressure, then my first book weight 1.5 lbs but volume did not change.  I added the second book that weight 1 lbs. for a total weight or pressure of 2.5lbs but my volume stayed the same.  It wasn't until book 3 that weight 3.5lbs for a total weight of 6lbs that my volume started to decrease.

·         Team Member C: I see that Team Member B and my graphs look similar but very unsure about my calculations of total pressure and PT*V. looking at Team B’s paper it seems as if I did indeed calculate them incorrectly.

3.    • What kind of changes would you make, if any, if you were to do this lab again? Include a discussion of differences between the individual data sets.

·         Team Member A:  Some changes that could have been made are using more accurate sensors and using containers that are less likely to leak. Additionally, ensuring that all participants read the experiment fully before starting would increase familiarity of the procedure and minimize human error. Repeating the experiment could also minimize the impact of an anomalous result.

·         Team Member B: I would like to use something better than a syringe with a cap.  While testing the pressure my cap kept popping off.  I had to repeat my experiment multiple time before the cap stopped popping off.  Also another thing I would change is maybe make it a bit easier to read or explain.  Also, just as Team Member A stated, to read the instructions first before starting the experiment.

·         Team Member C: Using more stable apparatus to make readings easier, trying to hold the books and take an accurate reading does not make for reliable results. Repeating the experiment multiple times would eliminate erroneous results. Understanding how to make graphs on excel would also make the experiment less error prone. All using the same weight of books at the same altitude would have made more uniform results.

4.    What are the real-world applications of the labs? In other words, why is the results or data from this lab important or used in the real world? This type of experiment or variation of it can be used in the real world for what purpose?

·         Team Member A:  According to the experiment, a real world application of Boyle's law are air-filled shock absorbers that are used in automobiles (Jeschofnig, 2012, "Boyle's Law"). 

·         Team Member B:    An example of real world application is a medical syringe.  As you inject the medication by applying pressure into the patient the volume goes down.  

·         Team Member C: An example of Boyles law in everyday life is spray paint. Spray paint works the way it does because it's actually a combination of paint and a gas propellant. During the manufacturing process, the cans are first filled with paint and then injected with the gas propellant. The valve is then crimped, trapping the highly compressed compound within the confines of the can. Today, most aerosols use hydro fluorocarbons, which consist of hydrogen, fluorine and carbon, When the nozzle is pressed, the paint-propellant mixture rushes up the dip tube in response to the sudden, dramatic change in pressure that causes the propellant in the can to expand, forcing the paint through the tube and out through the nozzle. The dip tube acts like a straw, with one end attached to the valve and the other end near the bottom of the can. Once through the dip tube, the nozzle and free of the pressurized can, the propellant expands and the paint atomizes into a fine, even mist. These tiny paint particles (not actually atoms) are evenly distributed because they are positively charged, repelling each other as they leave the can.

References:

Team Member A: 

Jeschofnig, P. (2012). General College Chemistry Lab Manual EXPERIMENTS. Retrieved from The University of Phoenix eBook Collection database.

Team Member C: How Stuff works,(2016). How spray pain works. Retrieved fromhttp://home.howstuffworks.com/spray-paint1.htm

LAB ASSISTANT Q&A’s

B.   Identify the shape of graph #2. Explain the graph.

·         Team Member A:  Answer: If v = k/p, then pv = k. The graph of pv against p should be a straight line parallel to the p-axis In other words, the product pv is a constant at a fixed temperature.

·         Team Member B:  It's a linear shape because it predicted Boyles law.

·         Team Member C: Graph 2 is a linear graph. Volume is inversely proportionate to pressure.

C.   Make a general statement concerning the relationship of pressure on the volume of a confined gas.

·         Team Member A:  Answer: Pressure is inversely proportional to the volume of a confined gas.

·         Team Member B: When pressure is decreased in a confined gas, the volume increases.-When pressure is increased in a  confined gas,  the volume decreases.

·         Team Member C: When pressure is increased on a confined gas, the volume is decreased. When pressure in decreased on confined gas the volume increases

D.  In your opinion, would the results be different if a different gas, like CO2 were used? Why?

·         Team Member A:  Answer: when different gas is used then results will be different due to difference in compressibility factor of the gas. Carbondioxide have compressibility factor is less than one at high and low pressure. But on the other hand, for other gas compressibility factor is different.

·         Team Member B: I think CO2 it would not change the results.  The gas wouldn't make a difference

·         Team Member C: Co2 is an ideal gas that takes up less percentage by volume that o2 or Nitrogen that make up the majority of room air. Room air also contains water vapor making it denser. Using Co2 would therefore change the results because it is a lighter gas.

E.   What is the air pressure in book units?

·         Team Member A:  Answer: The amount of force per unit area that air molecules exert on a surface is called air pressure by book unit.

·         Team Member B:  I was not able to figure this out

·         Team Member C: No answer

F.       Was the assumption of constant temperature valid for your experiment?

·         Team Member A:  Answer: For boyle’law pv = RT. So in the experiment the temperature had to remain constant.

·         Team Member B: Yes, because the temperature did not change.

·         Team Member C: Yes for the most part. Any changes in temperature would have been very minimal.

G.  Discuss the significance of the values obtained in the last column of the data table (P T * Vavg)

·         Team Member A:  Answer: P T * Vavg values in last column is almost same that is constant value should be obtained. Constant value indicates that PV versus V graph should be straight line parallel to V axis.

·         Team Member B: The product of the Pressure and the Volume is the value of k, the constant for the gas.

·         Team Member C: I am not at all sure I calculated theses correctly. I believe the product of the volume and the pressure is supposed to equal K which is the pressure of the gas.

H.  What are the possible sources of errors in your experiment?

·         Team Member A:  Answer: Boyle's Law assumes constant temperature, and the temperature could be changing during the experiment. So maintain a constant temperature is necessary. As you are adding water you are also adding water vapor, because some of the water will go into the gas phase. The vapor pressure of water at the temperature of your experiment is probably very small, but it could contribute. As the pressure increases, some of the gas may start dissolving more in the water, but that probably would also be a very small deviation. Improper setup could also cause error. Human error is always in effect.

·         Team Member B: Not having the cap sealed properly on the syringe tip.  Also I feel that the syringe was not very stable and I had to have help to sure the books on top and that might have gave me an incorrect reading.

·         Team Member C: Trying to stabilize the books and take readings was difficult which could lead to inaccurate results. Gas leakage or syringe friction could also affect the results.

I.             What could one do to minimize the errors in this experiment?

·         Team Member A: 

·         use more accurate sensors

·         use containers that are less likely to leak

·         ensure that I and my lab partners read the experiment beforehand (increasing familiarity with the procedure, and minimizing human error

·         repeat the experiment multiple times (to minimize the impact of an anomalous result).

·         Team Member B: Test the syringe pressure multiple times to make sure cap is securely on.  Have a better way to stabilize the syringe. 

·         Team Member C: More stable apparatus would make readings easier, than trying to balance books and take readings. Repeating the experiment multiple times would eliminate erroneous results. Understanding how to make graphs on excel would also make the experiment less error prone.

References

Team Member B:

David N. Blauch. (2000-2014). Gas Laws.  Retrieved from http://www.chm.davidson.edu/vce/gaslaws/boyleslawcalc.html