4(NH4)2S2O3 🔥→ 4HNO2 + (NH4)2S + 6H2S↑ + (NH4)2SO4
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Decomposition of ammonium thiosulfate yields nitrous acid, ammonium sulfide, hydrogen sulfide, and ammonium sulfate (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
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 | 4 | Reducing | Thermally decomposable Oxoacid salt |
Products
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| HNO2 | Nitrous acid | 4 | Oxidized | – |
| (NH4)2S | Ammonium sulfide | 1 | Reduced | – |
| H2S | Hydrogen sulfide | 6 | Reduced | – |
| (NH4)2SO4 | Ammonium sulfate | 1 | Oxidized | – |
Thermodynamic changes
Changes in aqueous solution (1)
- Decomposition of ammonium thiosulfate
- 4(NH4)2S2O3Aqueous solution4HNO2Un-ionized aqueous solution + (NH4)2SIonized aqueous solution + 6H2S↑Gas + (NH4)2SO4Ionized 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 | 1661.7 | – | – | – |
per 1 mol of | 415.43 | – | – | – |
per 1 mol of | 415.43 | – | – | – |
per 1 mol of | 1661.7 | – | – | – |
per 1 mol of | 276.95 | – | – | – |
per 1 mol of | 1661.7 | – | – | – |
Changes in aqueous solution (2)
- Decomposition of ammonium thiosulfate
- 4(NH4)2S2O3Aqueous solution4HNO2Un-ionized aqueous solution + (NH4)2SIonized aqueous solution + 6H2S↑Un-ionized aqueous solution + (NH4)2SO4Ionized 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 | 1547.3 | – | – | – |
per 1 mol of | 386.82 | – | – | – |
per 1 mol of | 386.82 | – | – | – |
per 1 mol of | 1547.3 | – | – | – |
per 1 mol of | 257.88 | – | – | – |
per 1 mol of | 1547.3 | – | – | – |
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 |
|---|---|---|---|---|
| HNO2 (g) cis | -77.99[1] | -42.94[1] | 248.76[1] | 44.77[1] |
| HNO2 (g) trans | -80.12[1] | -45.24[1] | 249.22[1] | 46.07[1] |
| HNO2 (g) | -79.5[1] | -46.0[1] | 254.1[1] | 45.6[1] |
| HNO2 (ao) | -119.2[1] | -50.6[1] | 135.6[1] | – |
| (NH4)2S (ai) | -231.8[1] | -72.6[1] | 212.1[1] | – |
| H2S (g) | -20.63[1] | -33.56[1] | 205.79[1] | 34.23[1] |
| H2S (ao) | -39.7[1] | -27.83[1] | 121[1] | – |
| (NH4)2SO4 (cr) | -1180.85[1] | -901.67[1] | 220.1[1] | 187.49[1] |
| (NH4)2SO4 (ai) | -1174.28[1] | -903.14[1] | 246.9[1] | -133.1[1] |
* (g):Gas, (ao):Un-ionized aqueous solution, (ai):Ionized aqueous solution, (cr):Crystalline solid
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°, -77.99 kJ · mol−1
- ^ ΔfG°, -42.94 kJ · mol−1
- ^ S°, 248.76 J · K−1 · mol−1
- ^ Cp°, 44.77 J · K−1 · mol−1
- ^ ΔfH°, -80.12 kJ · mol−1
- ^ ΔfG°, -45.24 kJ · mol−1
- ^ S°, 249.22 J · K−1 · mol−1
- ^ Cp°, 46.07 J · K−1 · mol−1
- ^ ΔfH°, -79.5 kJ · mol−1
- ^ ΔfG°, -46.0 kJ · mol−1
- ^ S°, 254.1 J · K−1 · mol−1
- ^ Cp°, 45.6 J · K−1 · mol−1
- ^ ΔfH°, -119.2 kJ · mol−1
- ^ ΔfG°, -50.6 kJ · mol−1
- ^ S°, 135.6 J · K−1 · mol−1
- ^ ΔfH°, -231.8 kJ · mol−1
- ^ ΔfG°, -72.6 kJ · mol−1
- ^ S°, 212.1 J · K−1 · mol−1
- ^ ΔfH°, -20.63 kJ · mol−1
- ^ ΔfG°, -33.56 kJ · mol−1
- ^ S°, 205.79 J · K−1 · mol−1
- ^ Cp°, 34.23 J · K−1 · mol−1
- ^ ΔfH°, -39.7 kJ · mol−1
- ^ ΔfG°, -27.83 kJ · mol−1
- ^ S°, 121. J · K−1 · mol−1
- ^ ΔfH°, -1180.85 kJ · mol−1
- ^ ΔfG°, -901.67 kJ · mol−1
- ^ S°, 220.1 J · K−1 · mol−1
- ^ Cp°, 187.49 J · K−1 · mol−1
- ^ ΔfH°, -1174.28 kJ · mol−1
- ^ ΔfG°, -903.14 kJ · mol−1
- ^ S°, 246.9 J · K−1 · mol−1
- ^ Cp°, -133.1 J · K−1 · mol−1