Which metals will react with 1 M H2SO4 to produce hydrogen gas?

• A. Na, Cd, and Pb only
• B. Na and Cd only
• C. Cu only
• D. Na, Cd, Pb, and Cu

Answer: (A)

When a metal is placed in an acid, hydrogen gas will be produced only if the metal can be oxidized more readily than hydrogen. In practical terms, this means the metal has a standard reduction potential more negative than that of the H+/H2 couple (0 V). Metals with such negative potentials will transfer electrons to the acid’s H+, forming H2, while the metal dissolves as M2+.

Sodium sits well above hydrogen in reactivity, so it readily reduces H+ and evolves H2, forming a salt like Na2SO4. Cadmium also has a negative reduction potential, so it will react with the acid to produce H2 and Cd2+. Lead is similarly more reducing than hydrogen, so it will react as well, giving Pb2+ (as PbSO4 in sulfuric acid) and hydrogen gas. Copper, on the other hand, has a reduction potential above hydrogen, so it does not reduce H+ in dilute sulfuric acid to produce hydrogen gas under these conditions.

Thus, the metals that will produce hydrogen gas with 1 M H2SO4 are sodium, cadmium, and lead; copper will not.