Chlorine dioxide (ClO₂), which is produced by the reaction

2NaClO₂(aq) + Cl₂(g)  →  2ClO₂(g) + 2NaCl(aq)

has been tested as a disinfectant for municipal water treatment.

a. Using data from Table 11.1, calculate ϐ^o, ΔG^o, and K at 25^oC for the production of ClO₂.

b. One of the concerns in using ClO₂ as a disinfectant is that the carcinogenic chlorate ion (ClO₃^-) might be a by-product. It can be formed from the reaction ClO₂(g) ⇌ ClO₃^-(aq) + Cl₂(aq) Balance the equation for the decomposition of ClO₂.

Table 11.1

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Standard Reduction Potentials at 25°G (298 K) for Many Common Haf-reactions Half-reaction %" (V) Half-reaction go (v) Og + 2H2O + 4e-→ 4OH Cu2+ + 2e-→ Cu F2 + 2e-→ 2F- 0.34 0.27 0.22 0.20 1.99 AgCl+ e-→ Ag+ Cl- SO42-+ 4H' + 2e-→ H2SO3+ H2O Cu2++ e-→ Cu" MnO4-+ 4H7 + 3e--> MnO, + 2H20 10c + 2H+ + 2e-→ io,-+ H,O Mndh" + 8H+ + 5e-→ Mn2+ 4H2O Fe3++ 3e-→ Fe Pb2++ 2e-→ Pb Sn2++ 2e-→ Sn Ni2++ 2e-→ Ni -0.036 PbO2 + 4H + + 2e--+ Pb2+ + 2H20 Cl2+ 2e-→ 2Cl -0.35 Fe2eFe 0, + 4H+ + 4e-→ 2H2O MnO, 4H+ + 2e-→ Mn2+ + 2H2O 1.21 1.20 Br2 2e2Br Zn2++ 2e-→ Zn 2H20 2eH2 20H -0.76 0.99 0.96 Al3eAl H2 2e2H Mg2+ +2e-→ M 2.23 -2.37 -2.76 -2.92 0.30 La't ter→ La 0.80 Na e Na + e-→ A Fe3++ e-→ Fe2+ Ba2+ + 2e--+ Ba 0.56 Li++ e-→ Li Cu teCu 0.52