Crystal radius and enthalpy of hydration of the cyanide ion.

Abstract
On the basis that the (electron density) crystal radius of the ion CN- is 1·77 Å, estimates have been made of the standard enthalpy of hydration of CN-(g) plus gaseous alkali metal ions. The results have been used in the derivation of the total lattice potential energies U POT(MCN) of alkali metal cyanides and other related thermochemical quantities. The following estimates have been made (298·15 K):