To range the metals copper, lead, silver and zinc together with hydrogen. Start with the strongest reducing agent.
The nobler a metal is, the worse reducing agent.
Sandpaper, strips of; zinc, lead, silver and copper, solutions containing aqueous; Zn2+, Pb2+, Cu2+ and Ag+ ions (0.2 M), hydrochloric acid (5.0 M), emery paper, test-tubes.
Burnish the three metal strips to get a shiny surface, after drop a drop of each of the metal ion solutions on the cleaned metal strips. Wash it off after a few minutes, and if there is patina present, record it. To test the reaction between the solids and hydrogen (H+) ions a small piece of each metal was dropped into a test-tube with 0.5 M hydrochloric acid.
The reaction formulas of the metals and the ions are as following:
Zn(s)+2H+(aq)->Zn2+ + H2
Zinc is the strongest reducing agent.
Zinc loses electrons most easily and is therefore oxidised. After zinc comes lead, followed by copper, while silver has least reducing ability of the metals studied in this lab.
The reducing ability of the metals was arrived at from the observations of patina formation on the metal plates. If the positive metal ions in the solutions are less powerful reducing agents, then the metal in the plate will be reduced and hence form a deposition of solid metal.
e.g. Zn + Pb2+-> Zn2+ + Pb
To range the halogens bromine, chlorine and iodine, with the strongest oxidising agent first.
A strong oxidising agent is a species that easily gains electrons, and is hence easily reduced. The ionisation energy of the halogens (Cl2, I2, Br2) decreases down the group,