5.2 The concentration of cyanide, CN–, in a copper electroplating bath can be determined by a complexometric titration with Ag+, forming the soluble Ag(CN2) – complex. In a typical analysis a 5.00‐mL sample from an electroplating bath is
transferred to a 250‐mL Erlenmeyer flask, and treated with 100 mL of H2O, 5 mL of 20% w/v NaOH and 5 mL of 10% w/v KI. The sample is titrated with 0.1012 M AgNO3, requiring 27.36 mL to reach the end point as signalled by the formation of a yellow precipitate of AgI. Report the concentration of cyanide as ppm of NaCN.