H2AsO4− + H2O → H3AsO4 + OH−
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- Reaction of dihydrogenarsenate ion and water
The reaction of dihydrogenarsenate ion and water yields arsenic acid and hydroxide ion. This reaction is an acid-base reaction and is classified as follows:
Table of contents
Reaction data
Chemical equation
- Reaction of dihydrogenarsenate ion and water
General equation
- Cation/AnionBrønsted base + H2OBrønsted acid ⟶ Proton donating ion/AcidConjugate acid + OH−Conjugate base
Oxidation state of each atom
- Reaction of dihydrogenarsenate ion and water
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| H2AsO4− | Dihydrogenarsenate ion | 1 | Brønsted base | Anion |
| H2O | Water | 1 | Brønsted acid | Water |
Products
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| H3AsO4 | Arsenic acid | 1 | Conjugate acid | Acid |
| OH− | Hydroxide ion | 1 | Conjugate base | Hydroxide ion |
Thermodynamic changes
Changes in standard condition (1)
- Reaction of dihydrogenarsenate ion and water◆
ΔrG 67.1 kJ/mol K 0.18 × 10−11 pK 11.76
| 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 | 62.9 | 67.1 | −14 | – |
per 1 mol of Dihydrogenarsenate ion | 62.9 | 67.1 | −14 | – |
per 1 mol of | 62.9 | 67.1 | −14 | – |
per 1 mol of | 62.9 | 67.1 | −14 | – |
per 1 mol of Hydroxide ion | 62.9 | 67.1 | −14 | – |
Changes in standard condition (2)
- Reaction of dihydrogenarsenate ion and water
| 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 | 60.8 | – | – | – |
per 1 mol of Dihydrogenarsenate ion | 60.8 | – | – | – |
per 1 mol of | 60.8 | – | – | – |
per 1 mol of | 60.8 | – | – | – |
per 1 mol of Hydroxide ion | 60.8 | – | – | – |
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 |
|---|---|---|---|---|
| H2AsO4− (ao) | -909.56[1] | -753.17[1] | 117[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] |
* (ao):Un-ionized aqueous solution, (cr):Crystalline solid, (l):Liquid, (g):Gas
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 |
|---|---|---|---|---|
| H3AsO4 (cr) | -906.3[1] | – | – | – |
| H3AsO4 (ao) | -902.5[1] | -766.0[1] | 184[1] | – |
| H3AsO4 (aq) | -904.6[1] | – | – | – |
| OH− (g) | -143.5[1] | – | – | – |
| OH− (ao) | -229.994[1] | -157.244[1] | -10.75[1] | -148.5[1] |
* (cr):Crystalline solid, (ao):Un-ionized aqueous solution, (aq):Aqueous solution, (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°, -909.56 kJ · mol−1
- ^ ΔfG°, -753.17 kJ · mol−1
- ^ S°, 117. 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
- ^ 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
- ^ ΔfH°, -143.5 kJ · mol−1
- ^ ΔfH°, -229.994 kJ · mol−1
- ^ ΔfG°, -157.244 kJ · mol−1
- ^ S°, -10.75 J · K−1 · mol−1
- ^ Cp°, -148.5 J · K−1 · mol−1