Calculating the Molar Volume of a Gas Experiment.
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Introduction
Molar Volume of a Gas Data Trial 1 Trial 2 Volume (cm3) ±0.5 37.0 cm3 40.4 cm3 Atmospheric Pressure (kPa) ±0.5 102.2 kPa 102.2 kPa Temperature of water (°C) ±0.5 19.0 °C 22.0 °C Calculations Moles of magnesium 1 meter of magnesium = 1.78 g ±0.01 ∴ 2 cm of magnesium = 1.78*2/100 = 0.0356 g ±0.01 Moles of Mg = Mass / Molar Mass Moles of Mg = 0.0356/24.31 = 0.00146 % uncertainty in moles = 0.01+0 = 0.01% % uncertainty to absolute uncertainty for moles = 0.01*0.00146/100 = 0.0000000464 ∴ Absolute uncertainty of moles = 0.00146000 mol ± 0.00000146 Trial 1 Partial Pressure of Hydrogen Partial Pressure of Hydrogen = Atmospheric Pressure – Vapor Pressure of water Partial Pressure of Hydrogen = 102.2 – 2.2 Partial Pressure of Hydrogen = 100.0 kPa % uncertainty for Atmospheric Pressure = 0.05/102.2*100 = 0. ...read more.
Middle
Volume Molar Volume = 23.7 dm3/mol % uncertainty for Volume = 2.01% % uncertainty for Moles = 0.01% % uncertainty for Molar Volume = 2.01+0.01 = 2.02% % uncertainty to absolute uncertainty for Molar Volume = 2.02*23.7/100 = ±8.52 ∴ Absolute uncertainty for Molar Volume = 23.7 dm3/mol ±8.52 Molar Volume = 23.7 dm3/mol ±8.52 Trial 2 Partial Pressure of Hydrogen Partial Pressure of Hydrogen = Atmospheric Pressure – Vapor Pressure Partial Pressure of Hydrogen = 102.2 – 2.6 Partial Pressure of Hydrogen = 99.6 kPa Volume occupied by one mole of hydrogen at STP P1V1/T1 = P2V2/T2 99.6*0.0404/295 = 100*V/273 V = 0.0372 dm3 Molar Volume Moles = Volume/Molar Volume 0.00146 = 0.0372/Molar Volume Molar Volume = 25.5 dm3/mol Average of both Trials = (25.5+23.7)/2 = 24.06 Evaluation I assumed that the temperature inside the eudiometer is equal to ...read more.
Conclusion
I used ideal gas law to find the volume occupied by one mole of hydrogen at STP but hydrogen is not an ideal gas. To get better results, I could have done more trials. Conclusion The aim of the experiment was to find the molar volume of Hydrogen. I got 24.06 (average) as the volume of one mole of hydrogen at STP. In the first trial, the molar volume found is 23.7 dm3/mol with an uncertainty of ±8.52. In the second trial, the molar volume is 25.5 dm3/mol. The molar volume of the second trial is higher because the yield of hydrogen in the second trial was higher than the first. The temperature in the second trial was higher as well. The theoretical results are 22.4 dm3. The difference is due to the errors made during the experiment and the assumptions I made. ...read more.
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