2HSCN + 6e− → 2S2− + 2CN− + H2↑
Last updated:
- Reduction of thiocyanic acid
Reduction of thiocyanic acid yields sulfide ion, cyanide ion, and (Other reactions are here). This reaction is an oxidation-reduction reaction and is classified as follows:
Table of contents
Reaction data
Chemical equation
- Reduction of thiocyanic acid
General equation
- Reduction of reducible species
- ReactantOxidizing agent + e− ⟶ ProductReduction product
Oxidation state of each atom
- Reduction of thiocyanic acid
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| HSCN | Thiocyanic acid | 2 | Oxidizing | – |
| e− | Electron | 6 | – | Electron |
Products
Thermodynamic changes
Changes in aqueous solution (1)
- Reduction of thiocyanic acid◆
ΔrG 331.0 kJ/mol K 0.10 × 10−57 pK 57.99 - 2HSCNIonized aqueous solution + 6e−2S2−Un-ionized aqueous solution + 2CN−Un-ionized aqueous solution + ↑Gas⟶
| Standard enthalpy of reaction ΔrH° kJ · mol−1 | Standard Gibbs energy of reaction ΔrG° kJ · mol−1 | Standard entropy of reaction ΔrS° J · K−1 · mol−1 | Standard heat capacity of reaction at constant pressure ΔrCp° J · K−1 · mol−1 | |
|---|---|---|---|---|
per 1 mol of Equation | 214.5 | 331.0 | 1.1 | – |
per 1 mol of | 107.3 | 165.5 | 0.55 | – |
per 1 mol of Electron | 35.75 | 55.17 | 0.18 | – |
per 1 mol of Sulfide ion | 107.3 | 165.5 | 0.55 | – |
per 1 mol of Cyanide ion | 107.3 | 165.5 | 0.55 | – |
| 214.5 | 331.0 | 1.1 | – |
Changes in aqueous solution (2)
- Reduction of thiocyanic acid◆
ΔrG 348.6 kJ/mol K 0.85 × 10−61 pK 61.07 - 2HSCNIonized aqueous solution + 6e−2S2−Un-ionized aqueous solution + 2CN−Un-ionized aqueous solution + ↑Un-ionized aqueous solution⟶
| Standard enthalpy of reaction ΔrH° kJ · mol−1 | Standard Gibbs energy of reaction ΔrG° kJ · mol−1 | Standard entropy of reaction ΔrS° J · K−1 · mol−1 | Standard heat capacity of reaction at constant pressure ΔrCp° J · K−1 · mol−1 | |
|---|---|---|---|---|
per 1 mol of Equation | 210.3 | 348.6 | 447 | – |
per 1 mol of | 105.2 | 174.3 | 224 | – |
per 1 mol of Electron | 35.05 | 58.10 | 74.5 | – |
per 1 mol of Sulfide ion | 105.2 | 174.3 | 224 | – |
per 1 mol of Cyanide ion | 105.2 | 174.3 | 224 | – |
| 210.3 | 348.6 | 447 | – |
Changes in aqueous solution (3)
- Reduction of thiocyanic acid◆
ΔrG 321.3 kJ/mol K 0.51 × 10−56 pK 56.29 - 2HSCNUn-ionized aqueous solution + 6e−2S2−Un-ionized aqueous solution + 2CN−Un-ionized aqueous solution + ↑Gas⟶
| Standard enthalpy of reaction ΔrH° kJ · mol−1 | Standard Gibbs energy of reaction ΔrG° kJ · mol−1 | Standard entropy of reaction ΔrS° J · K−1 · mol−1 | Standard heat capacity of reaction at constant pressure ΔrCp° J · K−1 · mol−1 | |
|---|---|---|---|---|
per 1 mol of Equation | – | 321.3 | – | – |
per 1 mol of | – | 160.7 | – | – |
per 1 mol of Electron | – | 53.55 | – | – |
per 1 mol of Sulfide ion | – | 160.7 | – | – |
per 1 mol of Cyanide ion | – | 160.7 | – | – |
| – | 321.3 | – | – |
Changes in aqueous solution (4)
- Reduction of thiocyanic acid◆
ΔrG 338.9 kJ/mol K 0.42 × 10−59 pK 59.37 - 2HSCNUn-ionized aqueous solution + 6e−2S2−Un-ionized aqueous solution + 2CN−Un-ionized aqueous solution + ↑Un-ionized aqueous solution⟶
| Standard enthalpy of reaction ΔrH° kJ · mol−1 | Standard Gibbs energy of reaction ΔrG° kJ · mol−1 | Standard entropy of reaction ΔrS° J · K−1 · mol−1 | Standard heat capacity of reaction at constant pressure ΔrCp° J · K−1 · mol−1 | |
|---|---|---|---|---|
per 1 mol of Equation | – | 338.9 | – | – |
per 1 mol of | – | 169.4 | – | – |
per 1 mol of Electron | – | 56.48 | – | – |
per 1 mol of Sulfide ion | – | 169.4 | – | – |
per 1 mol of Cyanide ion | – | 169.4 | – | – |
| – | 338.9 | – | – |
Thermodynamic data of reactants
| Chemical formula | Standard enthalpy of formation ΔfH° kJ · mol−1 | Standard Gibbs energy of formation ΔfG° kJ · mol−1 | Standard molar entropy S° J · K−1 · mol−1 | Standard molar heat capacity at constant pressure Cp° J · K−1 · mol−1 |
|---|---|---|---|---|
| HSCN (ai) | 76.44[1] | 92.71[1] | 144.3[1] | -40.2[1] |
| HSCN (ao) | – | 97.56[1] | – | – |
| e− | – | – | – | – |
* (ai):Ionized aqueous solution, (ao):Un-ionized aqueous solution
Thermodynamic data of products
| Chemical formula | Standard enthalpy of formation ΔfH° kJ · mol−1 | Standard Gibbs energy of formation ΔfG° kJ · mol−1 | Standard molar entropy S° J · K−1 · mol−1 | Standard molar heat capacity at constant pressure Cp° J · K−1 · mol−1 |
|---|---|---|---|---|
| S2− (ao) | 33.1[1] | 85.8[1] | -14.6[1] | – |
| CN− (ao) | 150.6[1] | 172.4[1] | 94.1[1] | – |
| (g) | 0[1] | 0[1] | 130.684[1] | 28.824[1] |
| (ao) | -4.2[1] | 17.6[1] | 577[1] | – |
* (ao):Un-ionized aqueous solution, (g):Gas
References
List of references
- 1Janiel J. Reed (1989)The NBS Tables of Chemical Thermodynamic Properties: Selected Values for Inorganic and C1 and C2 Organic Substances in SI UnitsNational Institute of Standards and Technology (NIST)
- ^ ΔfH°, 76.44 kJ · mol−1
- ^ ΔfG°, 92.71 kJ · mol−1
- ^ S°, 144.3 J · K−1 · mol−1
- ^ Cp°, -40.2 J · K−1 · mol−1
- ^ ΔfG°, 97.56 kJ · mol−1
- ^ ΔfH°, 33.1 kJ · mol−1
- ^ ΔfG°, 85.8 kJ · mol−1
- ^ S°, -14.6 J · K−1 · mol−1
- ^ ΔfH°, 150.6 kJ · mol−1
- ^ ΔfG°, 172.4 kJ · mol−1
- ^ S°, 94.1 J · K−1 · mol−1
- ^ ΔfH°, 0 kJ · mol−1
- ^ ΔfG°, 0 kJ · mol−1
- ^ S°, 130.684 J · K−1 · mol−1
- ^ Cp°, 28.824 J · K−1 · mol−1
- ^ ΔfH°, -4.2 kJ · mol−1
- ^ ΔfG°, 17.6 kJ · mol−1
- ^ S°, 577 J · K−1 · mol−1