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Each gas sample is the same size. However, the samples all weigh different amounts. In the video, the values were as follows (gases appear in the order given below):
|1. Vacuum (Calibration)||.000 g|
|2. Oxygen||.055/.054 g|
|3. Hydrogen||.011 g|
|4. Carbon Dioxide||.088 g|
|5. Sulfur Hexafluoride||.263 g|
Heavier gas samples weigh more than lighter ones. A gas sample cannot weigh more in this experiment by a change of volume, so the change must be related to the mass of the gas particles themselves.
Had the atomic/molecular weights of the gases been plotted against their experimental weights, it would have proven to be a straight line. There is a direct correlation between the atomic/molecular mass and the mass of a fixed sample (Avogadro's hypothesis, more or less). Using this hypothesis, a gas sample's atomic/molecular mass can be determined by simply weighing a fixed amount against a predetermined linear relationship.