Phosphoric Acid

• Formula: H₃O₄P
• Molecular weight: 97.9952
• IUPAC Standard InChI: InChI=1S/H3O4P/c1-5(2,3)4/h(H3,1,2,3,4) Copy

  
• IUPAC Standard InChIKey: NBIIXXVUZAFLBC-UHFFFAOYSA-N Copy
• CAS Registry Number: 7664-38-2
• Chemical structure:
  This structure is also available as a 2d Mol file or as a computed 3d SD file
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• Other names: Orthophosphoric acid; Phosphoric acid ortho; o-Phosphoric acid; Acide phosphorique; Acido fosforico; EVITs; Fosforzuuroplossingen; Phosphorsaeureloesungen; Sonac; UN 1805; H3PO4; Marphos; NFB; White phosphoric acid
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• Information on this page:
  • Condensed phase thermochemistry data
  • Reaction thermochemistry data
  • Gas phase ion energetics data
  • References
  • Notes
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Condensed phase thermochemistry data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Liquid Phase Heat Capacity (Shomate Equation)

C_p° = A + B*t + C*t² + D*t³ + E/t²
H° − H°_298.15= A*t + B*t²/2 + C*t³/3 + D*t⁴/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t²/2 + D*t³/3 − E/(2*t²) + G
    C_p = heat capacity (J/mol*K)
    H° = standard enthalpy (kJ/mol)
    S° = standard entropy (J/mol*K)
    t = temperature (K) / 1000.

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Solid Phase Heat Capacity (Shomate Equation)

C_p° = A + B*t + C*t² + D*t³ + E/t²
H° − H°_298.15= A*t + B*t²/2 + C*t³/3 + D*t⁴/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t²/2 + D*t³/3 − E/(2*t²) + G
    C_p = heat capacity (J/mol*K)
    H° = standard enthalpy (kJ/mol)
    S° = standard entropy (J/mol*K)
    t = temperature (K) / 1000.

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Reaction thermochemistry data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: John E. Bartmess

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

H₂O₄P^- +  =

By formula: H₂O₄P^- + H⁺ = H₃O₄P

Gas phase ion energetics data

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: John E. Bartmess

De-protonation reactions

H₂O₄P^- +  =

By formula: H₂O₄P^- + H⁺ = H₃O₄P

References

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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Morris, Knighton, et al., 1997
Morris, R.A.; Knighton, W.B.; Viggiano, A.A.; Hoffman, B.C.; Schaeffer III, H.F., The Gas-phase Acidity of H3PO4, J. Chem. Phys., 1997, 106, 9, 3545, https://doi.org/10.1063/1.473465 . [all data]

Notes

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• Symbols used in this document:
  

  S°liquid,1 bar	Entropy of liquid at standard conditions (1 bar)
  S°solid	Entropy of solid at standard conditions
  ΔfH°liquid	Enthalpy of formation of liquid at standard conditions
  ΔfH°solid	Enthalpy of formation of solid at standard conditions
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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