Activity Series Foothill Chemistry

Single Displacement Revisited Displacement of hydrogen in acid by metal (cations) Mg(s) + 2HCl(aq)  MgCl2(aq) + H2(g) Displacement of halogens (anions) 2NaBr(aq) + Cl2(g)  2NaCl(aq) + Br2(l) ** Halogens can only displace halides if they are higher on the periodic table than the one that is being replaced. Br2 + KCl(aq)  No Reaction

Metal Cation Displacement In order to determine the potential products of a chemical reaction, one must know whether or not a chemical reaction will occur. Similarly to the displacement of halogens, where their displacement depends on which anion is higher in the periodic table, metal cations depend on which cation is higher in the activity series.

Activity Series of Elements Most   Least Metals Li Rb K Ba Sr Ca Na Mg Al Mn Zn Cr Fe Cd Co Ni Sn Pb H2 Sb Bi Cu Hg Ag Pt Au Nonmetals F2 Cl2 Br2 I2

Predicting Products of Chemical Reactions Zn(s) + CuSO4(aq)  Cu(s) + ZnSO4(aq) Zinc is higher on the activity series, so it replaces copper Cu(s) + ZnSO4(aq)  Cu(s) + ZnSO4(aq) No Reaction so copper will not replace zinc

Salts Metals will only replace other metals when they are higher in the activity series. Cr(s) + ZnSO4(aq)  No Reaction Cr(s) + FeSO4(aq)  Fe(s) + CrSO4(aq) Mg(s) + CaCl2(aq)  No Reaction 3Mg(s) + Al2(SO4)3(aq)  2Al(s) + 3MgSO4(aq)

Application of Concept Can we silver-plate a gold object by immersing it in a solution of silver nitrate? NO Can we gold-plate a silver object by immersing it in a solution of gold (III) chloride? Yes

Reactions with Oxygen Elements at the top of the activity series rapidly oxidize The lower the element is on the activity series, the slower it will be to oxidize Platinum and gold do not oxidize.

Reducing Oxides Some metals can be used to deoxidize (reduce) other metals. 6FeO(s) + 4Al(s)  2Al2O3(s) + 6Fe(s) For Metals at the Top of the Activity Series, they must be reduced by electrolysis (application of an electric current) to remove oxygen For elements carbon and above (aluminum from back of periodic table) Some metal oxides can be reduced just by heating them (CuO, Hg2O) Some metals are so low on the activity series that they oxidize only indirectly (Pt, Au, Ag)

Reactions with Water K, Na and Ca react with cold water 2Na(s) + 2H2O(l)  2NaOH(aq) + H2 Mg, Zn, and Fe do not react with cold water, but they do react with steam Mg(s) + H2O (g)  MgO + H2 Cu, Ag, Au, and Pt do not react with water at all. Cu(s) + H2O (g)  No Reaction

Reactions with Acids The metals occurring above H2 on the activity series will replace hydrogen ions when reacted with acid. Na(s) + HCl(aq)  NaCl(aq) + H2 2Al(s) + 6HCl(aq)  AlCl3(aq) + 3H2 Au(s) + HCl(aq)  No Reaction

Noble Metals Cu, Hg, Ag, Au, Pt Ag, Au, Pt Do Not React with Steam Do Not React with HCl Ag, Au, Pt Do not React with HNO3 React With Aqua Regia Aqua Regia = 3HCl + 1HNO3

Summary