15.2 Exercise 20

In a titration of cyanide ion, 28.72 mL of 0.0100 M AgNO₃ is added before precipitation begins. [The reaction of Ag⁺ with CN^– goes to completion, producing the $\text{Ag} \left(\text{CN}\right)_{2} ^{−}$ complex.] Precipitation of solid AgCN takes place when excess Ag⁺ is added to the solution, above the amount needed to complete the formation of $\text{Ag} \left(\text{CN}\right)_{2} ^{−} .$ How many grams of NaCN were in the original sample?