2H3AsO4 🔥→ 2H3AsO3 + O2↑
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- Decomposition of arsenic acid
Decomposition of arsenic acid yields arsenous acid and (Other reactions are here). This reaction is an oxidation-reduction reaction and is classified as follows:
Table of contents
Reaction data
Chemical equation
- Decomposition of arsenic acid
General equation
- Thermal decomposition with redox
- Thermally decomposable substanceSelf redox agent🔥⟶ ProductOxidation product + ProductReduction product
Oxidation state of each atom
- Decomposition of arsenic acid
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| H3AsO4 | Arsenic acid | 2 | Self redox agent | Thermally decomposable |
Products
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| H3AsO3 | Arsenous acid | 2 | Reduced | – |
| 1 | Oxidized | – |
Thermodynamic changes
Changes in standard condition (1)
- Decomposition of arsenic acid◆
ΔrG 252.4 kJ/mol K 0.60 × 10−44 pK 44.22
| 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 | 320.6 | 252.4 | 227 | – |
per 1 mol of | 160.3 | 126.2 | 114 | – |
per 1 mol of | 160.3 | 126.2 | 114 | – |
| 320.6 | 252.4 | 227 | – |
Changes in standard condition (2)
- Decomposition of arsenic acid◆
ΔrG 268.8 kJ/mol K 0.81 × 10−47 pK 47.09
| 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 | 308.9 | 268.8 | 133 | – |
per 1 mol of | 154.4 | 134.4 | 66.5 | – |
per 1 mol of | 154.4 | 134.4 | 66.5 | – |
| 308.9 | 268.8 | 133 | – |
Changes in standard condition (3)
- Decomposition of 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 | 320.6 | – | – | – |
per 1 mol of | 160.3 | – | – | – |
per 1 mol of | 160.3 | – | – | – |
| 320.6 | – | – | – |
Changes in standard condition (4)
- Decomposition of 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 | 308.9 | – | – | – |
per 1 mol of | 154.4 | – | – | – |
per 1 mol of | 154.4 | – | – | – |
| 308.9 | – | – | – |
Changes in standard condition (5)
- Decomposition of 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 | 324.8 | – | – | – |
per 1 mol of | 162.4 | – | – | – |
per 1 mol of | 162.4 | – | – | – |
| 324.8 | – | – | – |
Changes in standard condition (6)
- Decomposition of 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 | 313.1 | – | – | – |
per 1 mol of | 156.6 | – | – | – |
per 1 mol of | 156.6 | – | – | – |
| 313.1 | – | – | – |
Changes in standard condition (7)
- Decomposition of 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 | 324.8 | – | – | – |
per 1 mol of | 162.4 | – | – | – |
per 1 mol of | 162.4 | – | – | – |
| 324.8 | – | – | – |
Changes in standard condition (8)
- Decomposition of 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 | 313.1 | – | – | – |
per 1 mol of | 156.6 | – | – | – |
per 1 mol of | 156.6 | – | – | – |
| 313.1 | – | – | – |
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 |
|---|---|---|---|---|
| H3AsO4 (cr) | -906.3[1] | – | – | – |
| H3AsO4 (ao) | -902.5[1] | -766.0[1] | 184[1] | – |
| H3AsO4 (aq) | -904.6[1] | – | – | – |
* (cr):Crystalline solid, (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 |
|---|---|---|---|---|
| H3AsO3 (ao) | -742.2[1] | -639.80[1] | 195.0[1] | – |
| H3AsO3 (aq) | -742.2[1] | – | – | – |
| (g) | 0[1] | 0[1] | 205.138[1] | 29.355[1] |
| (ao) | -11.7[1] | 16.4[1] | 110.9[1] | – |
* (ao):Un-ionized aqueous solution, (aq):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°, -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°, -742.2 kJ · mol−1
- ^ ΔfG°, -639.80 kJ · mol−1
- ^ S°, 195.0 J · K−1 · mol−1
- ^ ΔfH°, -742.2 kJ · mol−1
- ^ ΔfH°, 0 kJ · mol−1
- ^ ΔfG°, 0 kJ · mol−1
- ^ S°, 205.138 J · K−1 · mol−1
- ^ Cp°, 29.355 J · K−1 · mol−1
- ^ ΔfH°, -11.7 kJ · mol−1
- ^ ΔfG°, 16.4 kJ · mol−1
- ^ S°, 110.9 J · K−1 · mol−1