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H3PO4 → H+ + H2PO4

Electrolytic dissociation of phosphoric acid
H3PO4Phosphoric acid
H+Hydrogen ion + H2PO4Dihydrogenphosphate ion

Electrolytic dissociation of phosphoric acid yields hydrogen ion and dihydrogenphosphate 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
H+Hydrogen ion + H2PO4Dihydrogenphosphate 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 ion1
Hydrogen ion
H2PO4Dihydrogenphosphate ion1
Conjugate base
Anion

Thermodynamic changes

Changes in standard condition (1)

Electrolytic dissociation of phosphoric acid
ΔrG12.26 kJ/mol
K0.71 × 10−2
pK2.15
H3PO4Un-ionized aqueous solution
H+Un-ionized aqueous solution + H2PO4Un-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
−7.9512.26−67.8
per 1 mol of
−7.9512.26−67.8
per 1 mol of
Hydrogen ion
−7.9512.26−67.8
per 1 mol of
Dihydrogenphosphate ion
−7.9512.26−67.8

Changes in standard condition (2)

Electrolytic dissociation of phosphoric acid
ΔrG12.26 kJ/mol
K0.71 × 10−2
pK2.15
H3PO4Un-ionized aqueous solution
H+Un-ionized aqueous solution + H2PO4Un-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
−7.9512.26−67.8
per 1 mol of
−7.9512.26−67.8
per 1 mol of
Hydrogen ion
−7.9512.26−67.8
per 1 mol of
Dihydrogenphosphate ion
−7.9512.26−67.8

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]
H2PO4 (ao)-1296.29[1]-1130.28[1]90.4[1]
* (g):Gas, (ao):Un-ionized aqueous solution

References

List of references

  1. 1