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H3PO4 → 3H+ + PO43−

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Electrolytic dissociation of phosphoric acid
H3PO4Phosphoric acid
⟶
3H+Hydrogen ion + PO43−Phosphate ion

Electrolytic dissociation of phosphoric acid yields hydrogen ion and phosphate ion (Other reactions are here). 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 reactions
  5. 5Related categories

Reaction data

Chemical equation

Electrolytic dissociation of phosphoric acid
H3PO4Phosphoric acid
⟶
3H+Hydrogen ion + PO43−Phosphate ion

General equation

Electrolytic dissociation of acid
AcidBrønsted acid
⟶
H+ + AnionConjugate base

Oxidation state of each atom

Electrolytic dissociation of phosphoric acid

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
H3PO4Phosphoric acid1
Brønsted acid
Acid

Products

Chemical formulaNameCoefficientTypeType in general
equation
H+Hydrogen ion3
–
Hydrogen ion
PO43−Phosphate ion1
Conjugate base
Anion

Thermodynamic changes

Changes in standard condition (1)

Electrolytic dissociation of phosphoric acid
◆
ΔrG123.8 kJ/mol
K0.20 × 10−21
pK21.69
H3PO4Un-ionized aqueous solution
⟶
3H+Un-ionized aqueous solution + PO43−Un-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
10.9123.8−378.5–
per 1 mol of
10.9123.8−378.5–
per 1 mol of
Hydrogen ion
3.6341.27−126.2–
per 1 mol of
Phosphate ion
10.9123.8−378.5–

Changes in standard condition (2)

Electrolytic dissociation of phosphoric acid
◆
ΔrG123.8 kJ/mol
K0.20 × 10−21
pK21.69
H3PO4Un-ionized aqueous solution
⟶
3H+Un-ionized aqueous solution + PO43−Un-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
10.9123.8−378.5–
per 1 mol of
10.9123.8−378.5–
per 1 mol of
Hydrogen ion
3.6341.27−126.2–
per 1 mol of
Phosphate ion
10.9123.8−378.5–

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
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, (l):Liquid, (ai):Ionized aqueous solution, (ao):Un-ionized aqueous solution

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
H+ (g)1536.202[1]–––
H+ (ao)0[1]0[1]0[1]0[1]
PO43− (ao)-1277.4[1]-1018.7[1]-220.3[1]–
* (g):Gas, (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)