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MgO + H2O → Mg(OH)2

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Reaction of magnesium oxide and water
MgOMagnesium oxide + H2OWater
⟶
Mg(OH)2Magnesium hydroxide

The reaction of magnesium oxide and water yields magnesium hydroxide. This reaction is an acid-base reaction and is classified as follows:

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

Reaction data

Chemical equation

Reaction of magnesium oxide and water
MgOMagnesium oxide + H2OWater
⟶
Mg(OH)2Magnesium hydroxide

General equation

Reaction of basic oxide and water
Basic oxide + H2O
⟶
Base
Reaction of strongly basic oxide and water
Strongly basic oxide + H2O
⟶
Strong base

Oxidation state of each atom

Reaction of magnesium oxide and water

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
MgOMagnesium oxide1
–
Basic oxide
Strongly basic oxide
H2OWater1
–
Water

Products

Chemical formulaNameCoefficientTypeType in general
equation
Mg(OH)2Magnesium hydroxide1
–
Base
Strong base

Thermodynamic changes

Changes in standard condition (1)

Reaction of magnesium oxide and water
◆
ΔrG−30.43 kJ/mol
K2.14 × 105
pK−5.33
MgOCrystalline solid + H2OLiquid
⟶
Mg(OH)2Crystalline solid
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
−40.73−30.43−34.64−35.92
per 1 mol of
−40.73−30.43−34.64−35.92
per 1 mol of
−40.73−30.43−34.64−35.92
−40.73−30.43−34.64−35.92

Changes in standard condition (2)

Reaction of magnesium oxide and water
MgOCrystalline solid + H2OLiquid
⟶
Mg(OH)2Amorphous solidprecipitated
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
−36.7–––
per 1 mol of
−36.7–––
per 1 mol of
−36.7–––
−36.7–––

Changes in aqueous solution (1)

Reaction of magnesium oxide and water
◆
ΔrG−30.43 kJ/mol
K2.14 × 105
pK−5.33
MgOCrystalline solid + H2OLiquid
⟶
Mg(OH)2Crystalline solid
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
−40.73−30.43−34.64−35.92
per 1 mol of
−40.73−30.43−34.64−35.92
per 1 mol of
−40.73−30.43−34.64−35.92
−40.73−30.43−34.64−35.92

Changes in aqueous solution (2)

Reaction of magnesium oxide and water
MgOCrystalline solid + H2OLiquid
⟶
Mg(OH)2Amorphous solidprecipitated
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
−36.7–––
per 1 mol of
−36.7–––
per 1 mol of
−36.7–––
−36.7–––

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
MgO (cr)-597.98[1]-565.95[1]27.91[1]37.66[1]
MgO (g)17[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, (g):Gas, (l):Liquid

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
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]–
* (cr):Crystalline solid, (am):Amorphous solid, (g):Gas, (ai):Ionized aqueous solution

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)