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AlPO4 + 3H2O → Al(OH)3 + H3PO4

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Hydrolysis of aluminium phosphate
AlPO4Aluminium phosphate + 3H2OWater
⟶
Al(OH)3Aluminium hydroxide + H3PO4Phosphoric acid

The reaction of aluminium phosphate and water yields aluminium hydroxide and phosphoric acid. 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

Hydrolysis of aluminium phosphate
AlPO4Aluminium phosphate + 3H2OWater
⟶
Al(OH)3Aluminium hydroxide + H3PO4Phosphoric acid

General equation

Hydrolysis of salt
Salt of weak acid and weak baseBrønsted base + H2OBrønsted acid
⟶
Base/Basic saltConjugate base + Acid/Acid salt/HydrideConjugate acid

Oxidation state of each atom

Hydrolysis of aluminium phosphate

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
AlPO4Aluminium phosphate1
Brønsted base
Salt of weak acid and weak base
H2OWater3
Brønsted acid
Water

Products

Chemical formulaNameCoefficientTypeType in general
equation
Al(OH)3Aluminium hydroxide1
Conjugate base
Base
H3PO4Phosphoric acid1
Conjugate acid
Acid

Thermodynamic changes

Changes in standard condition (1)

Hydrolysis of aluminium phosphate
◆
ΔrG−96 kJ/mol
K6.58 × 1016
pK−16.82
AlPO4Crystalline solid + 3H2OLiquid
⟶
Al(OH)3Crystalline solid + H3PO4Crystalline 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
28−96−119−119.9
28−96−119−119.9
per 1 mol of
9.3−32−39.7−39.97
28−96−119−119.9
per 1 mol of
28−96−119−119.9

Changes in standard condition (2)

Hydrolysis of aluminium phosphate
AlPO4Crystalline solid + 3H2OLiquid
⟶
Al(OH)3Amorphous solid + H3PO4Crystalline 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
36–––
36–––
per 1 mol of
12–––
36–––
per 1 mol of
36–––

Changes in aqueous solution (1)

Hydrolysis of aluminium phosphate
◆
ΔrG−119 kJ/mol
K7.05 × 1020
pK−20.85
AlPO4Crystalline solid + 3H2OLiquid
⟶
Al(OH)3Crystalline solid + H3PO4Un-ionized aqueous solution
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
19−119−71–
19−119−71–
per 1 mol of
6.3−39.7−24–
19−119−71–
per 1 mol of
19−119−71–

Changes in aqueous solution (2)

Hydrolysis of aluminium phosphate
◆
ΔrG−119 kJ/mol
K7.05 × 1020
pK−20.85
AlPO4Crystalline solid + 3H2OLiquid
⟶
Al(OH)3Crystalline solid + H3PO4Un-ionized aqueous solution
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
19−119−71–
19−119−71–
per 1 mol of
6.3−39.7−24–
19−119−71–
per 1 mol of
19−119−71–

Changes in aqueous solution (3)

Hydrolysis of aluminium phosphate
◆
ΔrG5 kJ/mol
K0.13 × 100
pK0.88
AlPO4Crystalline solid + 3H2OLiquid
⟶
Al(OH)3Crystalline solid + H3PO4Ionized aqueous solution
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
305−450–
305−450–
per 1 mol of
102−150–
305−450–
per 1 mol of
305−450–

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
AlPO4 (cr)-1733.8[1]-1617.9[1]90.79[1]93.18[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, (l):Liquid, (g):Gas

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
Al(OH)3 (cr)-1284[2]-1306[2]71[2]93.1[2]
Al(OH)3 (am)-1276[1]–––
H3PO4 (cr)-1279.0[1]-1119.1[1]110.50[1]106.06[1]
H3PO4 (l)-1266.9[1]–––
H3PO4 (ai)-1277.4[1]-1018.7[1]-220.3[1]–
H3PO4 (ao)-1288.34[1]-1142.54[1]158.2[1]–
H3PO4 (cr)
0.5 hydrate
-1431.3[1]-1242.1[1]129.16[1]126.02[1]
H3PO4 (cr)
1 hydrate
-1568.83[1]–––
* (cr):Crystalline solid, (am):Amorphous solid, (l):Liquid, (ai):Ionized aqueous solution, (ao):Un-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)
    • 2
      James G. Speight (2017)
      Lange's Handbook of Chemistry, 17th edition
      McGraw Hill Education