1 (644)

Prévia do material em texto

20 Electrochemistry Solutions to Exercises 20.95 Table 4.5 is "The Activity Series of the Metals". Gold is the least active metal on this table, less active than copper. This means that gold is more difficult to oxidize than copper (and that for is more positive than for Cu²⁺). When crude copper is refined by electrolysis, Cu is oxidized from the crude anode, but any metallic gold present in the crude copper is not oxidized, so it accumulates near the anode, along with other impurities less active than copper. 20.96 The standard reduction potential for 0.57 V, is more positive than that of 0.34 V. This means the is "easier" to reduce than but Te is harder to oxidize and less active than Cu. During electrorefining, while Cu is oxidized from the crude anode, Te will not be oxidized. It is likely to accumulate along with other impurities less active than Cu, in the so-called anode sludge. Additional Exercises 20.97 (a) Ni(s) Ni⁺(aq) Ni²⁺(aq)+1e⁻ (b) 2[MnO₄²⁻(aq) (c) 3H₂SO₃(aq) (d) 4OH⁻(aq) Cl₂(aq)+4OH⁻(aq) 20.98 (a) e- V Anode (-) Cathode (+) Salt Bridge Pt H+ Pt Fe²⁺, Fe³⁺ anions cations 638