NaCN + HSCN → NaSCN + HCN
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The reaction of sodium cyanide and thiocyanic acid yields sodium thiocyanate and hydrogen cyanide. This reaction is an acid-base reaction and is classified as follows:
Table of contents
Reaction data
Chemical equation
- Reaction of sodium cyanide and thiocyanic acid
General equation
- Salt of volatile acidBrønsted base + Nonvolatile acidBrønsted acid ⟶ Salt of non volatile acidConjugate base + Volatile acidConjugate acid
Oxidation state of each atom
- Reaction of sodium cyanide and thiocyanic acid
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| NaCN | Sodium cyanide | 1 | Brønsted base | Salt of volatile acid |
| HSCN | Thiocyanic acid | 1 | Brønsted acid | Nonvolatile acid |
Products
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| NaSCN | Sodium thiocyanate | 1 | Conjugate base | Salt of non volatile acid |
| HCN | Hydrogen cyanide | 1 | Conjugate acid | Volatile acid |
Thermodynamic changes
Changes in aqueous solution (1)
- Reaction of sodium cyanide and thiocyanic acid◆
ΔrG −52.7 kJ/mol K 1.71 × 109 pK −9.23
| 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 | −43.5 | −52.7 | 30.6 | – |
per 1 mol of | −43.5 | −52.7 | 30.6 | – |
per 1 mol of | −43.5 | −52.7 | 30.6 | – |
per 1 mol of | −43.5 | −52.7 | 30.6 | – |
per 1 mol of | −43.5 | −52.7 | 30.6 | – |
Changes in aqueous solution (2)
- Reaction of sodium cyanide and thiocyanic acid◆
ΔrG −57.5 kJ/mol K 1.18 × 1010 pK −10.07
| 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 | – | −57.5 | – | – |
per 1 mol of | – | −57.5 | – | – |
per 1 mol of | – | −57.5 | – | – |
per 1 mol of | – | −57.5 | – | – |
per 1 mol of | – | −57.5 | – | – |
Changes in aqueous solution (3)
- Reaction of sodium cyanide and thiocyanic acid◆
ΔrG 0.0 kJ/mol K 1.00 × 100 pK 0.00
| 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 | 0.0 | 0.0 | 0.0 | – |
per 1 mol of | 0.0 | 0.0 | 0.0 | – |
per 1 mol of | 0.0 | 0.0 | 0.0 | – |
per 1 mol of | 0.0 | 0.0 | 0.0 | – |
per 1 mol of | 0.0 | 0.0 | 0.0 | – |
Changes in aqueous solution (4)
- Reaction of sodium cyanide and thiocyanic acid◆
ΔrG −4.8 kJ/mol K 6.93 × 100 pK −0.84
| 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 | – | −4.8 | – | – |
per 1 mol of | – | −4.8 | – | – |
per 1 mol of | – | −4.8 | – | – |
per 1 mol of | – | −4.8 | – | – |
per 1 mol of | – | −4.8 | – | – |
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 |
|---|---|---|---|---|
| NaCN (cr) cubic | -87.49[1] | -76.43[1] | 115.60[1] | 70.37[1] |
| NaCN (cr) orthorhombic | -90.75[1] | – | – | – |
| NaCN (g) | 109[1] | 79.94[1] | 249.43[1] | 51.17[1] |
| NaCN (ai) | -89.5[1] | -89.5[1] | 153.1[1] | – |
| NaCN (cr) 1/2 hydrate | -235.77[1] | – | – | – |
| NaCN (cr) 2 hydrate | -679.77[1] | – | – | – |
| HSCN (ai) | 76.44[1] | 92.71[1] | 144.3[1] | -40.2[1] |
| HSCN (ao) | – | 97.56[1] | – | – |
* (cr):Crystalline solid, (g):Gas, (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 |
|---|---|---|---|---|
| NaSCN (cr) | -170.50[1] | – | – | – |
| NaSCN (ai) | -163.68[1] | -169.18[1] | 203.3[1] | 6.3[1] |
| HCN (l) | 108.87[1] | 124.97[1] | 112.84[1] | 70.63[1] |
| HCN (g) | 135.1[1] | 124.7[1] | 201.78[1] | 35.86[1] |
| HCN (ai) | 150.6[1] | 172.4[1] | 94.1[1] | – |
| HCN (ao) | 107.1[1] | 119.7[1] | 124.7[1] | – |
* (cr):Crystalline solid, (ai):Ionized aqueous solution, (l):Liquid, (g):Gas, (ao):Un-ionized aqueous solution
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°, -87.49 kJ · mol−1
- ^ ΔfG°, -76.43 kJ · mol−1
- ^ S°, 115.60 J · K−1 · mol−1
- ^ Cp°, 70.37 J · K−1 · mol−1
- ^ ΔfH°, -90.75 kJ · mol−1
- ^ ΔfH°, 109. kJ · mol−1
- ^ ΔfG°, 79.94 kJ · mol−1
- ^ S°, 249.43 J · K−1 · mol−1
- ^ Cp°, 51.17 J · K−1 · mol−1
- ^ ΔfH°, -89.5 kJ · mol−1
- ^ ΔfG°, -89.5 kJ · mol−1
- ^ S°, 153.1 J · K−1 · mol−1
- ^ ΔfH°, -235.77 kJ · mol−1
- ^ ΔfH°, -679.77 kJ · mol−1
- ^ 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°, -170.50 kJ · mol−1
- ^ ΔfH°, -163.68 kJ · mol−1
- ^ ΔfG°, -169.18 kJ · mol−1
- ^ S°, 203.3 J · K−1 · mol−1
- ^ Cp°, 6.3 J · K−1 · mol−1
- ^ ΔfH°, 108.87 kJ · mol−1
- ^ ΔfG°, 124.97 kJ · mol−1
- ^ S°, 112.84 J · K−1 · mol−1
- ^ Cp°, 70.63 J · K−1 · mol−1
- ^ ΔfH°, 135.1 kJ · mol−1
- ^ ΔfG°, 124.7 kJ · mol−1
- ^ S°, 201.78 J · K−1 · mol−1
- ^ Cp°, 35.86 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°, 107.1 kJ · mol−1
- ^ ΔfG°, 119.7 kJ · mol−1
- ^ S°, 124.7 J · K−1 · mol−1