Abstract:

The purpose of this experiment is to determine how a reaction between an unknown metal and an acid can be used to identify the metal. In order to perform this lab, a sample of the unknown metal must be reacted with and acid in order to form hydrogen. The amount of hydrogen collected can be calculated from its pressure, volume, and temperature. An approximation of the atomic weight of the metal can also be calculated from the amount of hydrogen and the mass of the unknown metal sample. In order to identify the unknown, the released gas is first captured in a closed container with a known temperature and volume. The Ideal Gas Law, n= pV/RT, can then be used to calculate the number of moles of hydrogen. In this equation: n= number of moles of hydrogen released in the reaction (mol), p= partial pressure of hydrogen in the container (Pa or N/m^2), T= temperature of the hydrogen gas (k), and R= universal gas constant (J mol^(-1)K^(-1)). Then, using the number of moles of hydrogen released and applying each of the three possible stoichiometric ratios, the three atomic weights can be calculated. The three possible stoichiometric ratios, are as follows: 1). 2Me + 2H+ ---> 2Me+ + H2, 2). Me + 2H+ ---> Me^(2+) + H2, and

3). 2Me + 6H+ ---> 2Me^(3+) + 3H2. Finally, using the previous threee calculations and the physical properties of the unknown, a match can be found in the periodic table. As stated, the results of this lab will inevitably allow the idenfication and understanding of the unknown metal.