6H3AsO4 🔥→ 3As2O3 + 9H2O + 2O3↑
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- Decomposition of arsenic acid
Decomposition of arsenic acid yields diarsenic trioxide, water, 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 | 6 | Self redox agent | Thermally decomposable |
Products
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| As2O3 | Diarsenic trioxide | 3 | Reduced | – |
| H2O | Water | 9 | – | – |
| 2 | Oxidized | – |
Thermodynamic changes
Changes in standard condition (1)
- 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 | 1179.8 | – | – | – |
per 1 mol of | 196.63 | – | – | – |
per 1 mol of | 393.27 | – | – | – |
per 1 mol of | 131.09 | – | – | – |
| 589.90 | – | – | – |
Changes in standard condition (2)
- 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 | 1186.3 | – | – | – |
per 1 mol of | 197.72 | – | – | – |
per 1 mol of | 395.43 | – | – | – |
per 1 mol of | 131.81 | – | – | – |
| 593.15 | – | – | – |
Changes in aqueous solution (1)
- 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 | 1247.5 | – | – | – |
per 1 mol of | 207.92 | – | – | – |
per 1 mol of | 415.83 | – | – | – |
per 1 mol of | 138.61 | – | – | – |
| 623.75 | – | – | – |
Changes in aqueous solution (2)
- 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 | 1213.9 | – | – | – |
per 1 mol of | 202.32 | – | – | – |
per 1 mol of | 404.63 | – | – | – |
per 1 mol of | 134.88 | – | – | – |
| 606.95 | – | – | – |
Changes in aqueous solution (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 | 1260.1 | – | – | – |
per 1 mol of | 210.02 | – | – | – |
per 1 mol of | 420.03 | – | – | – |
per 1 mol of | 140.01 | – | – | – |
| 630.05 | – | – | – |
Changes in aqueous solution (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 | 1226.5 | – | – | – |
per 1 mol of | 204.42 | – | – | – |
per 1 mol of | 408.83 | – | – | – |
per 1 mol of | 136.28 | – | – | – |
| 613.25 | – | – | – |
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 |
|---|---|---|---|---|
| As2O3 (cr) octahedral | -656.97[1] | -576.22[1] | 107.1[1] | 95.65[1] |
| As2O3 (cr) monoclinic | -654.8[1] | -576.97[1] | 117[1] | – |
| As2O3 (g) | -604.6[1] | -548.9[1] | 191[1] | – |
| As2O3 (aq) | -626.8[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] |
| (g) | 142.7[1] | 163.2[1] | 238.93[1] | 39.20[1] |
| (ao) | 125.9[1] | 174.1[1] | 146[1] | – |
* (cr):Crystalline solid, (g):Gas, (aq):Aqueous solution, (l):Liquid, (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°, -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°, -656.97 kJ · mol−1
- ^ ΔfG°, -576.22 kJ · mol−1
- ^ S°, 107.1 J · K−1 · mol−1
- ^ Cp°, 95.65 J · K−1 · mol−1
- ^ ΔfH°, -654.8 kJ · mol−1
- ^ ΔfG°, -576.97 kJ · mol−1
- ^ S°, 117 J · K−1 · mol−1
- ^ ΔfH°, -604.6 kJ · mol−1
- ^ ΔfG°, -548.9 kJ · mol−1
- ^ S°, 191 J · K−1 · mol−1
- ^ ΔfH°, -626.8 kJ · 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°, 142.7 kJ · mol−1
- ^ ΔfG°, 163.2 kJ · mol−1
- ^ S°, 238.93 J · K−1 · mol−1
- ^ Cp°, 39.20 J · K−1 · mol−1
- ^ ΔfH°, 125.9 kJ · mol−1
- ^ ΔfG°, 174.1 kJ · mol−1
- ^ S°, 146. J · K−1 · mol−1