Chromium metal is added to a solution of nickel (ii) sulfate. what is the balanced chemical reaction? hints

(a) Nickel metal is added to a solution of copper (II) nitrate We have elemental Ni and Cu2 + (aq); on the activity series, Ni is above Cu. Therefore, Ni will be oxidized to the + 2 ion (look on the activity series) by Cu2 + (aq), and the Cu2 + will be reduced to elemental Cu: Ni (s) + Cu2 + (aq) - - > Ni2 + (aq) + Cu (s) This is a prime example of a single displacement reaction! (b) A solution of zinc nitrate is added to a solution of magnesium sulfate Here, we have aq solutions of Zn2 + and Mg2+. This is not a sinlge displacement reaction - neither of the reactant metals are in elemental form. This is a NR case - it is a double displacement reaction in which neither of the prodcuts are insoluble (why?) (c) Hydrochloric acid is added to gold metal Lok at the activity series: Au is at the very bottom. Au is below hydrogen and so will not react with hydrogen ions (H+). So this is an NR. (d) Hydrogen gas is bubbled through a solution of silver nitrate Here, we have elemental hydrogen and a solution of Ag+. Silver is below hydrogen on the activity series, so silver (I) ions will oxidize hydrogen gas. In net ionic form (be sure to work this one out!) 2Ag + (aq) + H2 (g) - - > 2Ag (s) + 2H + (aq)