Generating Hydrogen Gas

Chem Lab 2: Generation of Hydrogen Gas

Abstract:

Hydrogen gas was produced by the reaction of magnesium metal with hydrochloric acid. A small amount, 5.0 mL of diluted (6 M) hydrochloric acid was put into the eudiometer, and the remaining part of the eudiometer was filled with room temperature tap water. The magnesium ribbon, which is wrapped in copper wire acting like a cage, is placed in the eudiometer with a rubber stopper on top. Then the eudiometer is inverted and the stopper is placed underneath the surface of the water in a beaker. The hydrochloric acid diffuses down the eudiometer and contacts the magnesium metal, which creates the reaction. The water level in the eudiometer lowers and fills up the beaker it is sitting in, as the hydrogen gas is created. 3 trials of submerging a Mg(s) ribbon sample into diluted hydrochloric acid to produce H2(g) resulted in, on average, 101% of the predicted numbers of moles, with a standard deviation of 1.

Data and Results:

Trial 1

Trial 2

Trial 3

Predicted number moles Hydrogen

0.00146 mol

0.00159 mol

0.00136 mol

Pressure of hydrogen alone in eudiometer

730 mmHg

733 mm Hg

727 mm Hg

Conversions of temperature ºC to Kelvins

294.15 K

294.15 K

294.15 K

Conversions of volume from mL to L

0.0374 L

0.0399 L

0.0345 L

Moles of Hydrogen actually produced

0.00149 mol

0.00159 mol

0.00137 mol

Comparison values of predicted and actual moles of hydrogen

102%

100%

101%

Average percentage of hydrogen produced

101%

Standard deviation

1.00

%RSD

0.99%

Calculations:

Please refer to last pages.

Discussion:

The equation for the generation of hydrogen:

Mg(s) + 2HCl  MgCl2 + H2 (g)

1 mole magnesium plus two moles of hydrochloric acid gives 1 mole magnesium chloride plus hydrogen gas.

Since one mole of magnesium metal release one mole of...