H2SeO3 🔥→ Se + O2↑ + H2O
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- Decomposition of selenous acid
Decomposition of selenous acid yields , , and water (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 selenous acid
General equation
- Thermal decomposition with redox
- Thermally decomposable substanceSelf redox agent🔥⟶ ProductOxidation product + ProductReduction product
Oxidation state of each atom
- Decomposition of selenous acid
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| H2SeO3 | Selenous acid | 1 | Self redox agent | Thermally decomposable |
Products
Thermodynamic changes
Changes in standard condition (1)
- Decomposition of selenous 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 | 238.63 | – | – | – |
per 1 mol of | 238.63 | – | – | – |
| 238.63 | – | – | – | |
| 238.63 | – | – | – | |
per 1 mol of | 238.63 | – | – | – |
Changes in standard condition (2)
- Decomposition of selenous 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 | 245.3 | – | – | – |
per 1 mol of | 245.3 | – | – | – |
| 245.3 | – | – | – | |
| 245.3 | – | – | – | |
per 1 mol of | 245.3 | – | – | – |
Changes in aqueous solution (1)
- Decomposition of selenous acid◆
ΔrG 189.01 kJ/mol K 0.77 × 10−33 pK 33.11
| 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 | 221.65 | 189.01 | 109.6 | – |
per 1 mol of | 221.65 | 189.01 | 109.6 | – |
| 221.65 | 189.01 | 109.6 | – | |
| 221.65 | 189.01 | 109.6 | – | |
per 1 mol of | 221.65 | 189.01 | 109.6 | – |
Changes in aqueous solution (2)
- Decomposition of selenous acid◆
ΔrG 205.4 kJ/mol K 0.10 × 10−35 pK 35.98
| 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 | 210.0 | 205.4 | 15.4 | – |
per 1 mol of | 210.0 | 205.4 | 15.4 | – |
| 210.0 | 205.4 | 15.4 | – | |
| 210.0 | 205.4 | 15.4 | – | |
per 1 mol of | 210.0 | 205.4 | 15.4 | – |
Changes in aqueous solution (3)
- Decomposition of selenous 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 | 221.44 | – | – | – |
per 1 mol of | 221.44 | – | – | – |
| 221.44 | – | – | – | |
| 221.44 | – | – | – | |
per 1 mol of | 221.44 | – | – | – |
Changes in aqueous solution (4)
- Decomposition of selenous 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 | 209.7 | – | – | – |
per 1 mol of | 209.7 | – | – | – |
| 209.7 | – | – | – | |
| 209.7 | – | – | – | |
per 1 mol of | 209.7 | – | – | – |
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 |
|---|---|---|---|---|
| H2SeO3 (cr) | -524.46[1] | – | – | – |
| H2SeO3 (ao) | -507.48[1] | -426.14[1] | 207.9[1] | – |
| H2SeO3 (aq) | -507.27[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 |
|---|---|---|---|---|
| (cr) hexagonal, gray | 0[1] | 0[1] | 42.442[1] | 25.363[1] |
| (cr) monoclinic, red | 6.7[1] | – | – | – |
| (vit) | 5.0[1] | – | – | – |
| (g) | 227.07[1] | 187.03[1] | 176.72[1] | 20.820[1] |
| (g) | 0[1] | 0[1] | 205.138[1] | 29.355[1] |
| (ao) | -11.7[1] | 16.4[1] | 110.9[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] |
* (cr):Crystalline solid, (vit):Vitreous liquid, (g):Gas, (ao):Un-ionized aqueous solution, (l):Liquid
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°, -524.46 kJ · mol−1
- ^ ΔfH°, -507.48 kJ · mol−1
- ^ ΔfG°, -426.14 kJ · mol−1
- ^ S°, 207.9 J · K−1 · mol−1
- ^ ΔfH°, -507.27 kJ · mol−1
- ^ ΔfH°, 0 kJ · mol−1
- ^ ΔfG°, 0 kJ · mol−1
- ^ S°, 42.442 J · K−1 · mol−1
- ^ Cp°, 25.363 J · K−1 · mol−1
- ^ ΔfH°, 6.7 kJ · mol−1
- ^ ΔfH°, 5.0 kJ · mol−1
- ^ ΔfH°, 227.07 kJ · mol−1
- ^ ΔfG°, 187.03 kJ · mol−1
- ^ S°, 176.72 J · K−1 · mol−1
- ^ Cp°, 20.820 J · K−1 · 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
- ^ 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