Cyanide solution (12.73 mL) was treated with 25.00 mL of Ni2+ solution (containing excess Ni2+) to convert the cyanide into tetracyanonickelate(II):
4CN- + Ni2+ → Ni(CN)2-4
Excess Ni2+ was then titrated with 10.15 mL of 0.01307 M EDTA. Ni(CN)42- does not react with EDTA. If 39.35 mL of EDTA were required to react with 30.10 mL of the original Ni2+ solution, calculate the molarity of CN- in the 12.73 - mL sample.