Note 604 — Chapter XVI · SYSTEMATIC ANALYSIS FOR ACID IONS

In the calculation which follows, which is meant merely for a rough survey, no account is taken of the formation of complex ions I3−, or of the tendency of hydroiodic acid to decompose spontaneously into iodine and hydrogen: 2 H+ + 2 I− ⇄ H2 + I2, a reaction which could also be studied profitably with the aid of the equilibrium constants for I2 ⇄ 2 I− and for H2 ⇄ 2 H+. The value of the iodide constant is also uncertain (see p. 273).