(CN)2 (g): Dicyan or cyanogen, a covalent gaseous molecule.
ce{OH^- (aq): Hydroxide ion in aqueous solution, indicating basic medium.
ce{CN^- (aq): Cyanide ion, in solution.
ce{CNO^- (aq): Cyanate (or fulminate-related) type anion, in solution.
ce{H2O (l): Liquid water formed as a product.
2. Stoichiometric information
1 mole of \(\ce{(CN)2}\) reacts with 2 moles of \(\ce{OH^-}\).
Products contain 2 moles of \(\ce{CN^-}\) and 1 mole of \(\ce{CNO^-}\) per mole of \(\ce{(CN)2}\) consumed, plus 1 mole of water.
This allows mole–mole conversions, limiting reagent calculations, and yield predictions in quantitative problems.
3. Atom and charge balance
Carbon: LHS: 2 (in \(\ce{(CN)2}\)); RHS: 2 (in 2 CN^- + 1 (in \(\ce{CNO^- = 3 → implies the printed equation is often written with appropriate coefficients (the given form is typically schematic in textbooks).
Nitrogen, oxygen, hydrogen: From the pattern, one sees that OH⁻ provides both O and H to form water and the oxyanion \(\ce{CNO^-}\).
Charge: Total negative charge on LHS (2−) equals total negative charge on RHS (3−) in the symbolic equation, so the reaction is often understood as a simplified representation of a base-promoted transformation.
From a teaching perspective, the main idea is hydroxide attack on cyanogen giving cyanide and an oxyanion rather than strict redox balancing.
4. Reaction type and medium
The reaction occurs in basic aqueous medium (presence of OH^- (aq).
It is an example of nucleophilic attack of OH^- on a covalent molecule ce{(CN)2, producing anions CN^- and CNO^-.
Classified broadly as a hydrolysis / addition process in base, not a simple acid–base neutralisation.
5. Qualitative chemical information
(CN)2 is reactive towards strong bases and can generate cyanide in solution; this is relevant for toxicity and handling.
The appearance of {CNO^- indicates partial oxidation or rearrangement of the CN framework under basic conditions.
The reaction can be used to:
Prepare cyanide / cyanate solutions from cyanogen.
Illustrate nucleophilic additions to multiple bonds between identical atoms (C≡N–N≡C viewed collectively).