SCN− + 3H2O → S2− + HCO3− + NH3 + 2H+
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The reaction of thiocyanate ion and water yields sulfide ion, hydrogencarbonate ion, ammonia, and hydrogen ion (Other reactions are here). This reaction is an acid-base reaction and is classified as follows:
Table of contents
Reaction data
Chemical equation
- Reaction of thiocyanate ion and water
General equation
- Cation/AnionBrønsted acid + H2OBrønsted base ⟶ Proton accepting ion/BaseConjugate base + H+Conjugate acid
Oxidation state of each atom
- Reaction of thiocyanate ion and water
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| SCN− | Thiocyanate ion | 1 | Brønsted acid | Anion |
| H2O | Water | 3 | Brønsted base | Water |
Products
Thermodynamic changes
Changes in standard condition (1)
- Reaction of thiocyanate ion and water◆
ΔrG 101.3 kJ/mol K 0.18 × 10−17 pK 17.75
| 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 | 76.1 | 101.3 | −85.0 | – |
per 1 mol of Thiocyanate ion | 76.1 | 101.3 | −85.0 | – |
per 1 mol of | 25.4 | 33.77 | −28.3 | – |
per 1 mol of Sulfide ion | 76.1 | 101.3 | −85.0 | – |
per 1 mol of Hydrogencarbonate ion | 76.1 | 101.3 | −85.0 | – |
per 1 mol of | 76.1 | 101.3 | −85.0 | – |
per 1 mol of Hydrogen ion | 38.0 | 50.65 | −42.5 | – |
Changes in standard condition (2)
- Reaction of thiocyanate ion and water◆
ΔrG 91.2 kJ/mol K 0.11 × 10−15 pK 15.98
| 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 | 41.9 | 91.2 | −166.1 | – |
per 1 mol of Thiocyanate ion | 41.9 | 91.2 | −166.1 | – |
per 1 mol of | 14.0 | 30.4 | −55.37 | – |
per 1 mol of Sulfide ion | 41.9 | 91.2 | −166.1 | – |
per 1 mol of Hydrogencarbonate ion | 41.9 | 91.2 | −166.1 | – |
per 1 mol of | 41.9 | 91.2 | −166.1 | – |
per 1 mol of Hydrogen ion | 20.9 | 45.6 | −83.05 | – |
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 |
|---|---|---|---|---|
| SCN− (ao) | 76.44[1] | 92.71[1] | 144.3[1] | -40.2[1] |
| H2O (cr) | – | – | – | – |
| H2O (l) | -285.830[1] | -237.129[1] | 69.91[1] | 75.291[1] |
| H2O (g) | -241.818[1] | -228.572[1] | 188.825[1] | 33.577[1] |
* (ao):Un-ionized aqueous solution, (cr):Crystalline solid, (l):Liquid, (g):Gas
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] | – |
| HCO3− (ao) | -691.99[1] | -586.77[1] | 91.2[1] | – |
| NH3 (g) | -46.11[1] | -16.45[1] | 192.45[1] | 35.06[1] |
| NH3 (ao) | -80.29[1] | -26.50[1] | 111.3[1] | – |
| H+ (g) | 1536.202[1] | – | – | – |
| H+ (ao) | 0[1] | 0[1] | 0[1] | 0[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
- ^ ΔfH°, -285.830 kJ · mol−1
- ^ ΔfG°, -237.129 kJ · mol−1
- ^ S°, 69.91 J · K−1 · mol−1
- ^ Cp°, 75.291 J · K−1 · mol−1
- ^ ΔfH°, -241.818 kJ · mol−1
- ^ ΔfG°, -228.572 kJ · mol−1
- ^ S°, 188.825 J · K−1 · mol−1
- ^ Cp°, 33.577 J · K−1 · mol−1
- ^ ΔfH°, 33.1 kJ · mol−1
- ^ ΔfG°, 85.8 kJ · mol−1
- ^ S°, -14.6 J · K−1 · mol−1
- ^ ΔfH°, -691.99 kJ · mol−1
- ^ ΔfG°, -586.77 kJ · mol−1
- ^ S°, 91.2 J · K−1 · mol−1
- ^ ΔfH°, -46.11 kJ · mol−1
- ^ ΔfG°, -16.45 kJ · mol−1
- ^ S°, 192.45 J · K−1 · mol−1
- ^ Cp°, 35.06 J · K−1 · mol−1
- ^ ΔfH°, -80.29 kJ · mol−1
- ^ ΔfG°, -26.50 kJ · mol−1
- ^ S°, 111.3 J · K−1 · mol−1
- ^ ΔfH°, 1536.202 kJ · mol−1
- ^ ΔfH°, 0 kJ · mol−1
- ^ ΔfG°, 0 kJ · mol−1
- ^ S°, 0 J · K−1 · mol−1
- ^ Cp°, 0 J · K−1 · mol−1