Question 17.7: Consider the following reaction at 25°C: 3Ag(s) + NO3^-(aq) ...
Consider the following reaction at 25°C:
3Ag(s) + {NO_{3}}^{-}(aq) + 4H^+(aq) \longrightarrow 3Ag^+(aq) + NO(g) + 2H_2Oa Find ΔG°.
ANALYSIS
Information given: reaction: (3Ag(s) + {NO_{3}}^{-}(aq) + 4H^+(aq) \longrightarrow 3Ag^+(aq) + NO(g) + 2H_2O)
temperature (25°C)
Information implied: Table 17.1 (standard reduction potentials)
Faraday constant (F)
Asked for: ΔG°
STRATEGY
1. Assign oxidation numbers.
2. Split the redox reaction into oxidation and reduction half-reactions and find E°.
3. Determine the number of electrons cancelled out when balancing the equation to find n.
4. Substitute into Equation 17.2. Note that ΔG° will be in joules since the Faraday constant is in joules.
ΔG° = -nFE° (17.2)
b Find K.
ANALYSIS
Information given: From part (a): E° (0.165 V); n (3 mol)
Asked for: K
STRATEGY
Substitute into Equation 17.3.
E^{\circ} =\frac{ (0.0257\> V)}{n} \ln K (at 25°C) (17.3)
Table 17.1 Standard Potentials in Water Solution at 25°C | ||||
Acidic Solution, [H^+] = 1 M | ||||
{E^{\circ}}_{red} (V) | ||||
Li^+(aq) + e^- | \longrightarrow Li(s)\blacktriangleleft ⓘ | -3.04 | ||
K^+(aq) + e^- | \longrightarrow K(s) | -2.936 | ||
Ba^{2+}(aq) + 2e^{-} | \longrightarrow Ba(s) | -2.906 | ||
Ca^{2+}(aq) + 2e^- | \longrightarrow Ca(s) | -2.869 | ||
Na^+(aq) + e^- | \longrightarrow Na(s) | -2.714 | ||
Mg^{2+}(aq) + 2e^- | \longrightarrow Mg(s) | -2.357 | ||
Al^{3+}(aq) + 3e^- | \longrightarrow Al(s) | -1.68 | ||
Mn^{2+}(aq) + 2e^- | \longrightarrow Mn(s) | -1.182 | ||
Zn^{2+}(aq) + 2e^- | \longrightarrow Zn(s) | -0.762 | ||
Cr^{3+}(aq) + 3e^- | \longrightarrow Cr(s) | -0.744 | ||
Fe^{2+}(aq) + 2e^- | \longrightarrow Fe(s) | -0.409 | ||
Cr^{3+}(aq) + e^- | \longrightarrow Cr^{2+}(aq) | -0.408 | ||
Cd^{2+}(aq) + 2e^- | \longrightarrow Cd(s) | -0.402 | ||
PbSO_4(s) + 2e^- | \longrightarrow Pb(s) + {SO_4}^{2-}(aq) | -0.356 | ||
Tl^+(aq) + e^- | \longrightarrow Tl(s) | -0.336 | ||
Co^{2+}(aq) + 2e^- | \longrightarrow Co(s) | -0.282 | ||
Ni^{2+}(aq) + 2e^- | \longrightarrow Ni(s) | -0.236 | ||
AgI(s) + e^- | \longrightarrow Ag(s) + I^-(aq) | -0.152 | ||
Sn^{2+}(aq) + 2e^- | \longrightarrow Sn(s) | -0.141 | ||
Pb^{2+}(aq) + 2e^- | \longrightarrow Pb(s) | -0.127 | ||
2H^+(aq) + 2e^- | \longrightarrow H_2(g) | 0 | ||
AgBr(s) + e^- | \longrightarrow Ag(s) + Br^-(aq) | 0.073 | ||
S(s) + 2H^+(aq) + 2e^- | \longrightarrow H_2S(aq) | 0.144 | ||
Sn^{4+}(aq) + 2e^- | \longrightarrow Sn^{2+}(aq) | 0.154 | ||
{SO_4}^{2-}(aq) + 4H^+(aq) + 2e^- | \longrightarrow SO_2(g)+ 2H_2O | 0.155 | ||
Cu^{2+}(aq) + e^- | \longrightarrow Cu^+(aq) | 0.161 | ||
Cu^{2+}(aq) + 2e^- | \longrightarrow Cu(s) | 0.339 | ||
Cu^+(aq) + e^- | \longrightarrow Cu(s) | 0.518 | ||
I_2(s) + 2e^- | \longrightarrow 2I^-(aq) | 0.534 | ||
Fe^{3+}(aq) + e^- | \longrightarrow Fe^{2+}(aq) | 0.769 | ||
{Hg_2}^{2+}(aq) + 2e^- | \longrightarrow 2Hg(l) | 0.796 | ||
Ag^+(aq) + e^- | \longrightarrow Ag(s) | 0.799 | ||
2Hg^{2+}(aq) + 2e^- | \longrightarrow {Hg_{2}}^{2+}(aq) | 0.908 | ||
{NO_3}^-(aq) + 4H^+(aq) + 3e^- | \longrightarrow NO(g) + 2H_2O | 0.964 | ||
{AuCl_4}^-(aq) + 3e^- | \longrightarrow Au(s) + 4Cl^-(aq) | 1.001 | ||
Br_2(l) + 2e^- | \longrightarrow 2Br^-(aq) | 1.077 | ||
O_2(g) + 4H^+(aq) + 4e^- | \longrightarrow 2H_2O | 1.229 | ||
MnO_2(s) + 4H^+(aq) + 2e^- | \longrightarrow Mn^{2+}(aq) + 2H_2O | 1.229 | ||
{Cr_2O_7}^{2-}(aq) + 14H^+(aq) + 6e^- | \longrightarrow 2Cr^{3+}(aq) + 7H_2O | 1.33 | ||
Cl_2(g) + 2e^- | \longrightarrow 2Cl^-(aq) | 1.36 | ||
{ClO_3}^{-}(aq) + 6H^+(aq) + 5e^- | \longrightarrow \frac{1}{2} Cl_2(g) + 3H_2O | 1.458 | ||
Au^{3+}(aq) + 3e^- | \longrightarrow Au(s) | 1.498 | ||
{MnO_4}^{-}(aq) + 8H^+(aq) + 5e^- | \longrightarrow Mn^{2+}(aq) + 4H_2O | 1.512 | ||
PbO_2(s) + {SO_4}^{2-}(aq) + 4H^+(aq) + 2e^- | \longrightarrow PbSO_4(s) + 2H_2O | 1.687 | ||
H_2O_2(aq) + 2H^+(aq) + 2e^- | \longrightarrow 2H_2O | 1.763 | ||
Co^{3+}(aq) + e^- | \longrightarrow Co^{2+}(aq) | 1.953 | ||
F_2(g) + 2e^- \blacktriangleleft ⓘ | \longrightarrow 2F^-(aq) | 2.889 | ||
Basic Solution, [OH^-] = 1 M | ||||
{E^{\circ}}_{red} (V) | ||||
Fe(OH)_2(s) + 2e^- | \longrightarrow Fe(s) + 2OH^-(aq) | -0.891 | ||
2H_2O + 2e^- | \longrightarrow H_2(g) + 2OH^-(aq) | -0.828 | ||
Fe(OH)_3(s) + e^- | \longrightarrow Fe(OH)_2(s) + OH^-(aq) | -0.547 | ||
S(s) + 2e^- | \longrightarrow S^{2-}(aq) | -0.445 | ||
{NO_3}^{-}(aq) + 2H_2O + 3e^- | \longrightarrow NO(g) + 4OH^-(aq) | -0.14 | ||
{NO_3}^-(aq) + H_2O + 2e^- | \longrightarrow {NO_2}^-(aq) + 2OH^-(aq) | 0.004 | ||
{ClO_4}^-(aq) + H_2O + 2e^- | \longrightarrow {ClO_3}^-(aq) + 2OH^-(aq) | 0.398 | ||
O_2(g) + 2H_2O + 4e^- | \longrightarrow 4OH^-(aq) | 0.401 | ||
{ClO_3}^-(aq) + 3H_2O + 6e^- | \longrightarrow Cl^-(aq) + 6OH^-(aq) | 0.614 | ||
ClO^-(aq) + H_2O + 2e^- | \longrightarrow Cl^-(aq) + 2OH^-(aq) | 0.89 |
ⓘ Lithium is the strongest reducing agent.
ⓘ Lithium and fluorine are very dangerous materials to work with.
ⓘ O= strongest oxidizing agent;
R = strongest reducing agent.
ⓘ Fluorine is the strongest oxidizing agent.
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