5(NH4)2S2O3 🔥→ 2NH2OH + 4(NH4)2S + H2SO3 + 5SO2↑
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- Decomposition of ammonium thiosulfate
- 5(NH4)2S2O3Ammonium thiosulfate2NH2OHHydroxylamine + 4(NH4)2SAmmonium sulfide + H2SO3Sulfurous acid + 5SO2↑Sulfur dioxide🔥⟶
Decomposition of ammonium thiosulfate yields hydroxylamine, ammonium sulfide, sulfurous acid, and sulfur dioxide (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 thiosulfate
- 5(NH4)2S2O3Ammonium thiosulfate2NH2OHHydroxylamine + 4(NH4)2SAmmonium sulfide + H2SO3Sulfurous acid + 5SO2↑Sulfur dioxide🔥⟶
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 thiosulfate
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| (NH4)2S2O3 | Ammonium thiosulfate | 5 | Reducing | Thermally decomposable Oxoacid salt |
Products
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| NH2OH | Hydroxylamine | 2 | Oxidized | – |
| (NH4)2S | Ammonium sulfide | 4 | Reduced | – |
| H2SO3 | Sulfurous acid | 1 | Reduced | – |
| SO2 | Sulfur dioxide | 5 | Redoxed product | – |
Thermodynamic changes
Changes in aqueous solution (1)
- Decomposition of ammonium thiosulfate
- 5(NH4)2S2O3Aqueous solution2NH2OHAqueous solution + 4(NH4)2SIonized aqueous solution + H2SO3Un-ionized aqueous solution + 5SO2↑Gas🔥⟶
| 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 | 1368.7 | – | – | – |
per 1 mol of | 273.74 | – | – | – |
per 1 mol of Hydroxylamine | 684.35 | – | – | – |
per 1 mol of | 342.18 | – | – | – |
per 1 mol of | 1368.7 | – | – | – |
per 1 mol of | 273.74 | – | – | – |
Changes in aqueous solution (2)
- Decomposition of ammonium thiosulfate
- 5(NH4)2S2O3Aqueous solution2NH2OHAqueous solution + 4(NH4)2SIonized aqueous solution + H2SO3Un-ionized aqueous solution + 5SO2↑Un-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 | 1238.0 | – | – | – |
per 1 mol of | 247.60 | – | – | – |
per 1 mol of Hydroxylamine | 619.00 | – | – | – |
per 1 mol of | 309.50 | – | – | – |
per 1 mol of | 1238.0 | – | – | – |
per 1 mol of | 247.60 | – | – | – |
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)2S2O3 (aq) | -917.1[1] | – | – | – |
* (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 |
|---|---|---|---|---|
| NH2OH (cr) | -114.2[1] | – | – | – |
| NH2OH (aq) | -98.3[1] | – | – | – |
| (NH4)2S (ai) | -231.8[1] | -72.6[1] | 212.1[1] | – |
| H2SO3 (ao) | -608.81[1] | -537.81[1] | 232.2[1] | – |
| SO2 (l) | -320.5[1] | – | – | – |
| SO2 (g) | -296.830[1] | -300.194[1] | 248.22[1] | 39.87[1] |
| SO2 (ao) | -322.980[1] | -300.676[1] | 161.9[1] | – |
* (cr):Crystalline solid, (aq):Aqueous solution, (ai):Ionized aqueous solution, (ao):Un-ionized aqueous solution, (l):Liquid, (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°, -917.1 kJ · mol−1
- ^ ΔfH°, -114.2 kJ · mol−1
- ^ ΔfH°, -98.3 kJ · mol−1
- ^ ΔfH°, -231.8 kJ · mol−1
- ^ ΔfG°, -72.6 kJ · mol−1
- ^ S°, 212.1 J · K−1 · mol−1
- ^ ΔfH°, -608.81 kJ · mol−1
- ^ ΔfG°, -537.81 kJ · mol−1
- ^ S°, 232.2 J · K−1 · mol−1
- ^ ΔfH°, -320.5 kJ · mol−1
- ^ ΔfH°, -296.830 kJ · mol−1
- ^ ΔfG°, -300.194 kJ · mol−1
- ^ S°, 248.22 J · K−1 · mol−1
- ^ Cp°, 39.87 J · K−1 · mol−1
- ^ ΔfH°, -322.980 kJ · mol−1
- ^ ΔfG°, -300.676 kJ · mol−1
- ^ S°, 161.9 J · K−1 · mol−1