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5H2 + Mg3(AsO4)2 → 2As + 3Mg(OH)2 + 2H2O

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Reaction of hydrogen and magnesium arsenate
5H2Hydrogen + Mg3(AsO4)2Magnesium arsenate
⟶
2AsArsenic + 3Mg(OH)2Magnesium hydroxide + 2H2OWater

The reaction of hydrogen and magnesium arsenate yields arsenic, magnesium hydroxide, and water (Other reactions are here). This reaction is an oxidation-reduction reaction and is classified as follows:

Table of contents
  1. 1Reaction data
  2. 2Thermodynamic changes
  3. 3References
  4. 4Related reactions
  5. 5Related categories

Reaction data

Chemical equation

Reaction of hydrogen and magnesium arsenate
5H2Hydrogen + Mg3(AsO4)2Magnesium arsenate
⟶
2AsArsenic + 3Mg(OH)2Magnesium hydroxide + 2H2OWater

General equation

Reaction of reducing species and reducible species
Reducing speciesReducing agent + Reducible speciesOxidizing agent
⟶
ProductOxidation product + ProductReduction product

Oxidation state of each atom

Reaction of hydrogen and magnesium arsenate

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
H2Hydrogen5
Reducing
Reducing
Mg3(AsO4)2Magnesium arsenate1
Oxidizing
Reducible

Products

Chemical formulaNameCoefficientTypeType in general
equation
AsArsenic2
Reduced
–
Mg(OH)2Magnesium hydroxide3
Oxidized
–
H2OWater2
Oxidized
–

Thermodynamic changes

Changes in standard condition (1)

Reaction of hydrogen and magnesium arsenate
5H2Gas + Mg3(AsO4)2Crystalline solid
⟶
2AsCrystalline solidα, gray, metallic + 3Mg(OH)2Crystalline solid + 2H2OLiquid
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
−252.5–––
per 1 mol of
−50.50–––
per 1 mol of
−252.5–––
per 1 mol of
−126.3–––
−84.17–––
per 1 mol of
−126.3–––

Changes in standard condition (2)

Reaction of hydrogen and magnesium arsenate
5H2Gas + Mg3(AsO4)2Crystalline solid
⟶
2AsCrystalline solidα, gray, metallic + 3Mg(OH)2Amorphous solidprecipitated + 2H2OLiquid
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
−240.4–––
per 1 mol of
−48.08–––
per 1 mol of
−240.4–––
per 1 mol of
−120.2–––
−80.13–––
per 1 mol of
−120.2–––

Changes in standard condition (3)

Reaction of hydrogen and magnesium arsenate
5H2Gas + Mg3(AsO4)2Crystalline solid
⟶
2AsCrystalline solidγ, yellow, cubic + 3Mg(OH)2Crystalline solid + 2H2OLiquid
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
−223.3–––
per 1 mol of
−44.66–––
per 1 mol of
−223.3–––
per 1 mol of
−111.7–––
−74.43–––
per 1 mol of
−111.7–––

Changes in standard condition (4)

Reaction of hydrogen and magnesium arsenate
5H2Gas + Mg3(AsO4)2Crystalline solid
⟶
2AsCrystalline solidγ, yellow, cubic + 3Mg(OH)2Amorphous solidprecipitated + 2H2OLiquid
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
−211.2–––
per 1 mol of
−42.24–––
per 1 mol of
−211.2–––
per 1 mol of
−105.6–––
−70.40–––
per 1 mol of
−105.6–––

Changes in standard condition (5)

Reaction of hydrogen and magnesium arsenate
5H2Gas + Mg3(AsO4)2Crystalline solid
⟶
2AsAmorphous solidβ + 3Mg(OH)2Crystalline solid + 2H2OLiquid
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
−244.1–––
per 1 mol of
−48.82–––
per 1 mol of
−244.1–––
per 1 mol of
−122.0–––
−81.37–––
per 1 mol of
−122.0–––

Changes in standard condition (6)

Reaction of hydrogen and magnesium arsenate
5H2Gas + Mg3(AsO4)2Crystalline solid
⟶
2AsAmorphous solidβ + 3Mg(OH)2Amorphous solidprecipitated + 2H2OLiquid
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
−232.0–––
per 1 mol of
−46.40–––
per 1 mol of
−232.0–––
per 1 mol of
−116.0–––
−77.33–––
per 1 mol of
−116.0–––

Changes in aqueous solution (1)

Reaction of hydrogen and magnesium arsenate
5H2Un-ionized aqueous solution + Mg3(AsO4)2Crystalline solid
⟶
2AsCrystalline solidα, gray, metallic + 3Mg(OH)2Crystalline solid + 2H2OLiquid
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
−231.5–––
per 1 mol of
−46.30–––
per 1 mol of
−231.5–––
per 1 mol of
−115.8–––
−77.17–––
per 1 mol of
−115.8–––

Changes in aqueous solution (2)

Reaction of hydrogen and magnesium arsenate
5H2Un-ionized aqueous solution + Mg3(AsO4)2Crystalline solid
⟶
2AsCrystalline solidα, gray, metallic + 3Mg(OH)2Amorphous solidprecipitated + 2H2OLiquid
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
−219.4–––
per 1 mol of
−43.88–––
per 1 mol of
−219.4–––
per 1 mol of
−109.7–––
−73.13–––
per 1 mol of
−109.7–––

Thermodynamic data of reactants

Chemical formulaStandard 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
H2 (g)0[1]0[1]130.684[1]28.824[1]
H2 (ao)-4.2[1]17.6[1]577[1]–
Mg3(AsO4)2 (cr)-3092.8[1]–––
* (g):Gas, (ao):Un-ionized aqueous solution, (cr):Crystalline solid

Thermodynamic data of products

Chemical formulaStandard 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
As (cr)
α, gray, metallic
0[1]0[1]35.1[1]24.64[1]
As (cr)
γ, yellow, cubic
14.6[1]–––
As (am)
β
4.2[1]–––
As (g)302.5[1]261.0[1]174.21[1]20.786[1]
Mg(OH)2 (cr)-924.54[1]-833.51[1]63.18[1]77.03[1]
Mg(OH)2 (am)
precipitated
-920.5[1]–––
Mg(OH)2 (g)-561[1]–––
Mg(OH)2 (ai)-926.84[1]-769.4[1]-159.4[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, (am):Amorphous solid, (g):Gas, (ai):Ionized aqueous solution, (l):Liquid

References

List of references

  1. 1
    Janiel J. Reed (1989)
    The NBS Tables of Chemical Thermodynamic Properties: Selected Values for Inorganic and C1 and C2 Organic Substances in SI Units
    National Institute of Standards and Technology (NIST)