According to the table of standard reduction potentials at 25 o C, The equilibrium constant for the reaction, Sn(s) + 2 H + → Sn 2+ + H 2 (g) at 25 o C is:(根据下面25 o C时的标准还原电位表,以上反应在25 o C时的平衡常数是:) half reaction E o , V Ca 2+ + 2 e - → Ca -2.87 Zn 2+ + 2 e - -→ Zn -0.76 Sn 2+ + 2 e - → Sn -0.14 2 H + + 2 e - → H 2 (g) 0.00 Ag + + e - → Ag +0.80 NO 3 - + 4 H + + 3 e - → NO(g) + 2 H 2 O +0.96 Au 3+ + 3 e - → Au +1.50