A handbook gives the value E° = 0.174 V for the reduction half-reaction S + 2 H⁺ + 2 e^– → H₂S(g). In Figure 22-13, the value given for the segment S—H₂S(aq) is 0.144 V. Why are these E° values different? Can both be correct?

Figure 22-13

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Acidic solution ([H+] = 1 M): +6 +5 -0.22 V SO4²- -S₂06²- 0.158 V SO4²-- 0.564 V -0.936 V Basic solution ([OH-] = 1 M): +6 +4 +4 SO3²-- SO₂(aq)- -0.576 V 0.507 V +2 +2.5 -S₂03²-- -0.66 V -S406²- -0.74 V 0.080 V 0.449 V 0 +2 S -S₂03²-- -2 -0.476 V S²- 0 0.465 V 0.144 V S -2 -H₂S(aq)