Note 406 — Chapter XI · THE COPPER AND SILVER GROUPS. PRECIPITATION WITH HYDROGEN SULPHIDE
Reading edition
On account of the presence of a small, unknown amount of sulphuric acid in the original solution, resulting from the hydrolysis of ferrous sulphate, the exact value of [S2−] in the first solution cannot be calculated without further examination; but, according to the values given in the table on page 202, the value of x, indicating the growth in the concentration of S2−, is at least 1012, if 2 equivalents of NaOH, and 109, if 2 equivalents of NH4OH are used to convert the 0.1 molar hydrogen sulphide into the corresponding sulphide Me2S, of 0.1 molar concentration.