3KCN + H3AsO4 → K3AsO4 + 3HCN
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The reaction of potassium cyanide and arsenic acid yields potassium arsenate and hydrogen cyanide. This reaction is an acid-base reaction and is classified as follows:
Table of contents
Reaction data
Chemical equation
- Reaction of potassium cyanide and arsenic 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 potassium cyanide and arsenic acid
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| KCN | Potassium cyanide | 3 | Brønsted base | Salt of volatile acid |
| H3AsO4 | Arsenic acid | 1 | Brønsted acid | Nonvolatile acid |
Products
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| K3AsO4 | Potassium arsenate | 1 | Conjugate base | Salt of non volatile acid |
| HCN | Hydrogen cyanide | 3 | Conjugate acid | Volatile acid |
Thermodynamic changes
Changes in aqueous solution (1)
- Reaction of potassium cyanide and arsenic acid◆
ΔrG −40.4 kJ/mol K 1.20 × 107 pK −7.08
| 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 | −116.4 | −40.4 | −255 | – |
per 1 mol of | −38.80 | −13.5 | −85.0 | – |
per 1 mol of | −116.4 | −40.4 | −255 | – |
per 1 mol of | −116.4 | −40.4 | −255 | – |
per 1 mol of | −38.80 | −13.5 | −85.0 | – |
Changes in aqueous solution (2)
- Reaction of potassium cyanide and arsenic acid
| 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 | −114.3 | – | – | – |
per 1 mol of | −38.10 | – | – | – |
per 1 mol of | −114.3 | – | – | – |
per 1 mol of | −114.3 | – | – | – |
per 1 mol of | −38.10 | – | – | – |
Changes in aqueous solution (3)
- Reaction of potassium cyanide and arsenic acid◆
ΔrG 117.7 kJ/mol K 0.24 × 10−20 pK 20.62
| 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 | 14.1 | 117.7 | −347 | – |
per 1 mol of | 4.70 | 39.23 | −116 | – |
per 1 mol of | 14.1 | 117.7 | −347 | – |
per 1 mol of | 14.1 | 117.7 | −347 | – |
per 1 mol of | 4.70 | 39.23 | −116 | – |
Changes in aqueous solution (4)
- Reaction of potassium cyanide and arsenic acid
| 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 | 16.2 | – | – | – |
per 1 mol of | 5.40 | – | – | – |
per 1 mol of | 16.2 | – | – | – |
per 1 mol of | 16.2 | – | – | – |
per 1 mol of | 5.40 | – | – | – |
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 |
|---|---|---|---|---|
| KCN (cr) | -113.0[1] | -101.86[1] | 128.49[1] | 66.27[1] |
| KCN (g) | 90.8[1] | 64.17[1] | 261.90[1] | 52.34[1] |
| KCN (ai) | -101.7[1] | -110.9[1] | 196.6[1] | – |
| H3AsO4 (cr) | -906.3[1] | – | – | – |
| H3AsO4 (ao) | -902.5[1] | -766.0[1] | 184[1] | – |
| H3AsO4 (aq) | -904.6[1] | – | – | – |
* (cr):Crystalline solid, (g):Gas, (ai):Ionized aqueous solution, (ao):Un-ionized aqueous solution, (aq):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 |
|---|---|---|---|---|
| K3AsO4 (ai) | -1645.27[1] | -1498.23[1] | 144.8[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] | – |
* (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°, -113.0 kJ · mol−1
- ^ ΔfG°, -101.86 kJ · mol−1
- ^ S°, 128.49 J · K−1 · mol−1
- ^ Cp°, 66.27 J · K−1 · mol−1
- ^ ΔfH°, 90.8 kJ · mol−1
- ^ ΔfG°, 64.17 kJ · mol−1
- ^ S°, 261.90 J · K−1 · mol−1
- ^ Cp°, 52.34 J · K−1 · mol−1
- ^ ΔfH°, -101.7 kJ · mol−1
- ^ ΔfG°, -110.9 kJ · mol−1
- ^ S°, 196.6 J · K−1 · mol−1
- ^ ΔfH°, -906.3 kJ · mol−1
- ^ ΔfH°, -902.5 kJ · mol−1
- ^ ΔfG°, -766.0 kJ · mol−1
- ^ S°, 184. J · K−1 · mol−1
- ^ ΔfH°, -904.6 kJ · mol−1
- ^ ΔfH°, -1645.27 kJ · mol−1
- ^ ΔfG°, -1498.23 kJ · mol−1
- ^ S°, 144.8 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