4(NH4)3AsO4 🔥→ 12NH2OH + 3AsH3↑ + H3AsO4
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- Decomposition of ammonium arsenate
Decomposition of ammonium arsenate yields hydroxylamine, , and arsenic acid (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 ammonium arsenate
General equation
- Thermal decomposition with redox
- Thermally decomposable substanceSelf redox agent🔥⟶ ProductOxidation product + ProductReduction product
- Thermal decomposition of oxoacid salt with redox
- Oxoacid saltSelf redox agent🔥⟶ ProductOxidation product + ProductReduction product
Oxidation state of each atom
- Decomposition of ammonium arsenate
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| (NH4)3AsO4 | Ammonium arsenate | 4 | Self redox agent | Thermally decomposable Oxoacid salt |
Products
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| NH2OH | Hydroxylamine | 12 | Oxidized | – |
| 3 | Reduced | – | ||
| H3AsO4 | Arsenic acid | 1 | – | – |
Thermodynamic changes
Changes in standard condition
- Decomposition of ammonium arsenate
| 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 | 3067.4 | – | – | – |
per 1 mol of | 766.85 | – | – | – |
per 1 mol of Hydroxylamine | 255.62 | – | – | – |
| 1022.5 | – | – | – | |
per 1 mol of | 3067.4 | – | – | – |
Changes in aqueous solution (1)
- Decomposition of ammonium arsenate
- 4(NH4)3AsO4Ionized aqueous solution12NH2OHAqueous solution + 3↑Gas + H3AsO4Un-ionized aqueous solution🔥⟶
| 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 | 3259.9 | – | – | – |
per 1 mol of | 814.98 | – | – | – |
per 1 mol of Hydroxylamine | 271.66 | – | – | – |
| 1086.6 | – | – | – | |
per 1 mol of | 3259.9 | – | – | – |
Changes in aqueous solution (2)
- Decomposition of ammonium arsenate
| 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 | 3257.8 | – | – | – |
per 1 mol of | 814.45 | – | – | – |
per 1 mol of Hydroxylamine | 271.48 | – | – | – |
| 1085.9 | – | – | – | |
per 1 mol of | 3257.8 | – | – | – |
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 |
|---|---|---|---|---|
| (NH4)3AsO4 (cr) | -1286.2[1] | – | – | – |
| (NH4)3AsO4 (ai) | -1285.66[1] | -886.32[1] | 177.4[1] | – |
| (NH4)3AsO4 (cr) 3 hydrate | -2166.9[1] | – | – | – |
* (cr):Crystalline solid, (ai):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 |
|---|---|---|---|---|
| NH2OH (cr) | -114.2[1] | – | – | – |
| NH2OH (aq) | -98.3[1] | – | – | – |
| (g) | 66.44[1] | 68.93[1] | 222.78[1] | 38.07[1] |
| H3AsO4 (cr) | -906.3[1] | – | – | – |
| H3AsO4 (ao) | -902.5[1] | -766.0[1] | 184[1] | – |
| H3AsO4 (aq) | -904.6[1] | – | – | – |
* (cr):Crystalline solid, (aq):Aqueous solution, (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°, -1286.2 kJ · mol−1
- ^ ΔfH°, -1285.66 kJ · mol−1
- ^ ΔfG°, -886.32 kJ · mol−1
- ^ S°, 177.4 J · K−1 · mol−1
- ^ ΔfH°, -2166.9 kJ · mol−1
- ^ ΔfH°, -114.2 kJ · mol−1
- ^ ΔfH°, -98.3 kJ · mol−1
- ^ ΔfH°, 66.44 kJ · mol−1
- ^ ΔfG°, 68.93 kJ · mol−1
- ^ S°, 222.78 J · K−1 · mol−1
- ^ Cp°, 38.07 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