Molar Volume and the Universal Gas Constant

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9. The balanced equation that represents what happened in this reaction is

Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g).

10. The experimental value for the universal gas constant ( R ) is 0.0840. The experimental value of 0.0821 to our value of 0.0840 is 2.3%.

PV/nT=R (721.24-23.76)=697.48/760=0.9177 atm (0.9177)(0.042)/(0.00154)(298)=R

R=0.0840 0.0821/0.0840=0.977 1-0.977=0.023(100)=2.3%

Conclusion

Reflecting on this lab, we learned how to determine the volume of hydrogen that produced when a sample of magnesium metal reacts with hydrogen chloride dissolved in water. The chemical theories that have been demonstrated in this lab are STP. STP is the standard temperature and pressure, known as 22.4 L/mol for all gases. With the results, we were also able to figure out the constant R, which is 0.0821. We received as answer very close to R, but not the same. The first step in the experiment was to gather magnesium and copper. We folded up the magnesium strips and wrapped the copper wire around the strips of magnesium. Next, we filled up a beaker ⅔ full. Then, putting a gas measuring tube on a clamp, we tilted it and poured 10 mL of hydrochloric acid with 1 mL of red dye; the red dye is used to see the hydrochloric acid better. We then poured some water from the beaker into the tube until it overflowed. We flipped the tube covering the hole so that no air escaped and put it in water. The hydrochloric acid sank to the magnesium and reacted, producing little bubbles. We then took all of the gas that reacted to a large jar and balanced out the pressure and measured the volume of the gas. There were still some air bubbles on the side of the tube, which could have affected the lab. Then lastly, we poured out the contents and cleaned everything up.

The results of our lab were a little over the expected results. Our volume for hydrogen gas was 42 mL. This created the 23.7 L/mol as well as our constant R 0.0840. Our results were pretty accurate comparing the expected 2.4 L/mol and receiving 23.7 L/mol. This was only a 5.5% percentage error. Small mistakes such as letting in air while transporting the gas measuring tube could have been our downfall for getting a higher number. Our expected constant of R read to be 0.0821, but with our results, we found out that we received 0.0840. This has a 2.3% percentage error, meaning with did an overall good job on collecting our data. Our results were very close to the expected result and we had no big mistakes that could cause our outlier, so we were successful in this lab. In contrast, we were not exactly correct. This could have been caused by errors that are unavoidable. One big error could have been air bubbles stuck to the side of the gas measuring tube. We were supposed to get rid of them all but it was very difficult. This changed our L/mol ratio and changed our mathematical answers as well. In this lab, I learned how to find any gas’s molar volume at standard temperature and pressure (STP). I also learned more about how the constant R and STP are involved in ideal gas laws.