hcn and kcn have similar chemical formulas. however, 0.1 m hcn has a ph of 5.2, while 0.1 m kcn has a ph of 11.2. why do these two compounds behave so differently when they dissolve in water? hcn has a great solubility. hcn is an acid, and kcn is a salt. kcn is much stronger base than hcn. hcn is a nonelectrolyte.