More puzzling is the fact that when nickel, copper or platinum is placed in contact with zinc, bubbles form on the other metal's surface.

Only zinc (E o red of Zn 2+ = -0.762 V) meets this standard. Although the E o's for the reduction of Ni 2+ and Pb 2+ to the metals are slightly negative (-0.257 and -0.125 V), experience demonstrates that the reduction potential must be less than -0.6 V before reduction of H + will take place. Examination of a table of standard reduction potentials indicates that copper and platinum should not reduce H + to H 2. The first set of observations is easily explained. No gas isgenerated at the lead strip when the metals are separated in thesolution but connected by an external wire, since lead's overvoltageis higher than zinc's overvoltage. When the two metalstouch, still no bubbles are generated at the lead strip. Lead and Zinc in HCl Play movie(QuickTime 3.0 Sorenson, duration 28 seconds, size 2 MB)Ī zinc strip placed in hydrochloric acid generates gas bubbles,but a lead strip in the same solution does not. When a lead strip is placed in hydrochloric acid, no reactionoccurs. Lead in HCl Play movie(QuickTime 3.0 Sorenson, duration 6 seconds, size 430 K) When a wire isplaced across the two metal strips outside the solution, with thestrips not touching inside the solution, again gas is generated atthe platinum strip. When the two metalstouch, gas is also generated at the platinum strip. Platinum and Zinc in HCl Play movie(QuickTime 3.0 Sorenson, duration 29 seconds, size 2 MB)Ī zinc strip placed in hydrochloric acid generates bubbles, but aplatinum strip in the same solution does not. When a platinum strip is placed in hydrochloric acid, no reactionoccurs. Platinum in HCl Play movie(QuickTime 3.0 Sorenson, duration 6 seconds, size 450 K) When a wire isplaced across the two metal strips outside the solution, with thestrips not touching inside the solution, again gas is generated atthe copper strip. When the two metalstouch, gas is also generated at the copper strip. When a copper strip is placed in hydrochloric acid, no reactionoccurs.Ĭopper and Zinc in HCl Play movie(QuickTime 3.0 Sorenson, duration 36 seconds, size 2.5 MB)Ī zinc strip placed in hydrochloric acid generates gas bubbles,but a copper strip in the same solution does not. When a wire isplaced across the two metal strips outside the solution, with thestrips not touching inside the solution, again gas is generated atthe nickel strip.Ĭopper in HCl Play movie(QuickTime 3.0 Sorenson, duration 9 seconds, size 660 K) When the two metalstouch, gas is also generated at the nickel strip. Nickel and Zinc in HCl Play movie(QuickTime 3.0 Sorenson, duration 33 seconds, size 2.3 MB)Ī zinc strip placed in hydrochloric acid generates gas bubbles,but a nickel strip in the same solution does not. When a nickel strip is placed in hydrochloric acid, no reactionoccurs. Nickel in HCl Play movie(QuickTime 3.0 Sorenson, duration 7 seconds, size 520 K) When a zinc strip is placed in hydrochloric acid, a reactionoccurs, generating hydrogen gas bubbles. Zinc in HCl Play movie(QuickTime 3.0 Sorenson, duration 9 seconds, size 751.2 K) The following variations are presented below. However, when a piece oflead is brought in contact with the zinc, no bubbles are observed onthe surface of the lead.ĭescriptive chemistry, electrochemical (galvanic) cells, halogens/halides/hydrohalic acids, metals, reactivity - kinetic/thermodynamic stability, redox reaction, zinc When nickel,copper or platinum is connected electrically to the zinc externally (through a wire), bubbles againform on the surface of each of these metals. Hydrogen also forms on the surfaces ofcopper and platinum when those metals touch the zinc. When nickel dipped inhydrochloric acid is brought in contact with zinc, bubbles form onthe surface of the nickel metal.

Zinc metal reacts with hydrochloric acid, generating hydrogen gas.However, when a strip of nickel, copper, platinum or lead is placedin hydrochloric acid, no reaction is observed.

Hydrochloric acid reactivity