Background Info:

Metals that have a more negative reduction potential than H+ ions can reduce H+ ions to H2.  A sample of the unknown metal can be reacted with an acid and the hydrogen formed can be collected.  The amount of hydrogen collected can be calculated from its pressure, volume, and temperature.  From the amount of hydrogen and the mass of the unknown metal sample, an approximation of the atomic weight of the metal can be calculated based on all three stoichiometric possibilities. 

In this lab, to identify the unknown metal, it is reacted in an acid and the released hydrogen gas is captured in a closed container.  The volume and temperature of the container is known.  Then, to find the number of moles of hydrogen, the ideal gas law is applied to determine the results.  By applying each of the three stoichiometric ratios, the number of moles of hydrogen can be used in calculating the atomic weights.  From all of the data, a match can be found from the properties presented in the elements on the periodic table.