Summary: Magnesium, mossy zinc and copper foil are reacted with hydrochloric acid to produce hydrogen gas and a salt. The reaction rates are compared.
Hydrochloric acid is corrosive and toxic.
The hydrogen reaction product is flammable.
Chemicals and Solutions:
Test tubes, hydrometer cylinders or crystallization dishes, 3 each.
3 test tubes
in test tube rack
3 hydrometer cylinders
3 crystallization dishes
Add HCl to just more than cover each metal.
Hint: If using the test tube racks or hydrometer cylinders, cover with enough acid (a couple of inches at least) so that the bubbles are obvious, making their up through the solution. The crystallization dishes work well if presenting the demo on the overhead.
Magnesium reacts rapidly forming hydrogen and magnesium chloride.
Mg(s) + HCl(aq) èMgCl2(aq) + H2(g)
Zinc reacts more slowly than the magnesium, forming hydrogen and zinc chloride.
Zn(s) + HCl(aq) èZnCl2(aq) + H2(g)
Copper does not react with HCl.
(More accurately, copper reacts slowly enough that appears not to react for the lecture period.)