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REDOX REACTIONS 251 reducing agent than the H /H couple.2A information from them. The values of standard positive E  means that the redox couple is a electrode potentials for some selected electrode + weaker reducing agent than the H /H 2ouple. processes (reduction reactions) are given in The standard electrode potentials are very Table 7.1. You will learn more about electrode important and we can get a lot of other useful reactions and cells in Class XII. Table 7.1 The Standard Electrode Potentials at 298 K Ions are present as aqueous species and H O2as liquid; gases and solids are shown by g and s respectively. Reaction (Oxidised form + ne – → Reduced form) E / V – – F 2g) + 2e → 2F 2.87 Co 3++ e– → Co 2+ 1.81 H 2O2+ 2H + 2e – → 2H 2 1.78 – + – 2+ MnO 4 + 8H + 5e → Mn + 4H2O 1.51 Au 3++ 3e– → Au(s) 1.40 Cl2(g) + 2e → 2Cl – 1.36 2– + – 3+ Cr 2 7 + 14H + 6e → 2Cr + 7H 2 1.33 O (g) + 4H + 4e– → 2H O 1.23 2 2 MnO 2(s) + 4H + 2e– → Mn 2+ + 2H2O 1.23 – – Br 2+ 2e → 2Br 1.09 t NO –+ 4H + 3e – → NO(g) + 2H O t 0.97 e 3 2 e g 2Hg 2++ 2e – → Hg 22+ a 0.92 g + – g n Ag + e → Ag(s) i 0.80 i Fe 3++ e– → Fe 2+ c 0.77 i d x O 2(g) + 2H + 2e– → H 2 2 r 0.68 f – – f o I2(s) + 2e → 2I o 0.54 h Cu + + e → Cu(s) t 0.52 g g e Cu 2++ 2e– → Cu(s) e 0.34 t – – t s AgCl(s) + e → Ag(s) + Cl s 0.22 g – – n i AgBr(s) + e → Ag(s) + Br s 0.10 a 2H + + 2e– → H (g) a 0.00 r 2 r c Pb 2++ 2e– → (s) n –0 13 I 2+ – I Sn + 2e → n(s) –0 1 Ni2+ + 2e– → i(s) –0 25 Fe 2++ 2e– → e(s) –0 3+ – Cr + 3e → Cr(s) –0 7 Zn 2++ 2e– → n(s) –0 7 – – 2H 2 + 2e → H 2g) + 2OH –0 3 Al3++ 3e – → l(s) –1 Mg 2++ 2e – → g(s) –2 3 + – Na + e → a(s) –2 71 Ca 2++ 2e– → Ca(s) –2 7 K ++ e– → (s) –2 3 + – Li + e → i(s) –3 05 1. Anegative E means that the redox couple is a stronger reducing agent than the H /H couple.  + 2 2. Apositive E means that the redox couple is a weaker reducing agent t2an the H /H couple. Reprint 2026-27