Mg3(AsO4)2 🔥→ 3MgO + As2O5
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- Decomposition of magnesium arsenate
Decomposition of magnesium arsenate yields magnesium oxide and diarsenic pentaoxide (Other reactions are here). This reaction is an acid-base reaction and is classified as follows:
- Thermal decomposition without redox
- Thermal decomposition of oxoacid salt without redox
- Thermal decomposition of salt of oxoacid and hydroxide base
Table of contents
Reaction data
Chemical equation
- Decomposition of magnesium arsenate
General equation
- Thermal decomposition without redox
- Thermally decomposable substanceLewis conjugate🔥⟶ ProductLewis acid + ProductLewis base
- Thermal decomposition of oxoacid salt without redox
- Oxoacid saltLewis conjugate🔥⟶ Basic oxideLewis base + Acidic oxideLewis acid + (H2O)
- Thermal decomposition of salt of oxoacid and hydroxide base
- Salt of oxoacid and hydroxide baseLewis conjugate🔥⟶ Basic oxideLewis base + Acidic oxideLewis acid
Oxidation state of each atom
- Decomposition of magnesium arsenate
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| Mg3(AsO4)2 | Magnesium arsenate | 1 | Lewis conjugate | Thermally decomposable Oxoacid salt Salt of oxoacid and hydroxide base |
Products
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| MgO | Magnesium oxide | 3 | Lewis acid Lewis base | – Basic oxide |
| As2O5 | Diarsenic pentaoxide | 1 | Lewis acid | – Acidic oxide |
Thermodynamic changes
Changes in standard condition
- Decomposition of magnesium 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 | 374.0 | – | – | – |
per 1 mol of | 374.0 | – | – | – |
per 1 mol of | 124.7 | – | – | – |
per 1 mol of | 374.0 | – | – | – |
Changes in aqueous solution
- Decomposition of magnesium 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 | 347.5 | – | – | – |
per 1 mol of | 347.5 | – | – | – |
per 1 mol of | 115.8 | – | – | – |
per 1 mol of | 347.5 | – | – | – |
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 |
|---|---|---|---|---|
| Mg3(AsO4)2 (cr) | -3092.8[1] | – | – | – |
* (cr):Crystalline solid
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 |
|---|---|---|---|---|
| MgO (cr) | -597.98[1] | -565.95[1] | 27.91[1] | 37.66[1] |
| MgO (g) | 17[1] | – | – | – |
| As2O5 (cr) | -924.87[1] | -782.3[1] | 105.4[1] | 116.52[1] |
| As2O5 (aq) | -951.4[1] | – | – | – |
| As2O5 (cr) 4 hydrate | -2104.6[1] | – | – | – |
* (cr):Crystalline solid, (g):Gas, (aq):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°, -3092.8 kJ · mol−1
- ^ ΔfH°, -597.98 kJ · mol−1
- ^ ΔfG°, -565.95 kJ · mol−1
- ^ S°, 27.91 J · K−1 · mol−1
- ^ Cp°, 37.66 J · K−1 · mol−1
- ^ ΔfH°, 17. kJ · mol−1
- ^ ΔfH°, -924.87 kJ · mol−1
- ^ ΔfG°, -782.3 kJ · mol−1
- ^ S°, 105.4 J · K−1 · mol−1
- ^ Cp°, 116.52 J · K−1 · mol−1
- ^ ΔfH°, -951.4 kJ · mol−1
- ^ ΔfH°, -2104.6 kJ · mol−1