Phosphoric Acid

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  • Identifiers

    CAS number
    7664-38-2

    Molecular formula
    H3O4P

    SMILES
    OP(=O)(O)O

    Safety labels

    Corrosive
    Corrosive

  • Odor profile

    Fragrance
    Odorless 76.91%
    Sour 23.21%
    Sharp 17.79%
    Clean 16.59%
    Sulfurous 15.62%
    Pungent 15.48%
    Savory 12.27%
    Green 12.21%
    Sweaty 12.18%
    Cheesy 12.1%

     

    Flavor
    Odorless 66.75%
    Sour 40.96%
    Vinegar 34.08%
    Pungent 32.34%
    Sharp 24.41%
    Acidic 22.66%
    Rancid 22.15%
    Formyl 21.72%
    Bland 21.15%
    Soy 20.84%

     

    Odor impact est.
    Low

  • Properties

    XLogP3-AA
    -2.1

    pKa est.
    5.77 (weak acid)

    Molecular weight
    97.995 g/mol

    Melting point expt.

    • 108 °F (NIOSH, 2024)
    • 42.4 °C
    • Melting point: 75% -17.5 °C; 80% 4.6 °C; 85% 21 °C.
    • Hygroscopic; Latent heat of fusion = 10.5 kJ/mol at the melting point; Heat capacity at constant pressure = 106.2 J/mole (25 °C).
    • White, monoclinic crystalline solid; MP; melts at 42.35 °C; the hemihydrate has a melting point of 29.25 °C /Pure, 100% phosphoric acid/
    • 41.00 to 44.00 °C. @ 760.00 mm Hg
    • 42 °C
    • 21.1 °C
    • 108 °F

    Boiling point

    • greater than 266 °F at 760 mmHg (USCG, 1999)
    • 407 °C
    • 3.4 (Air = 1 at the boiling point of phosphoric acid)
    • 158.00 °C. @ 760.00 mm Hg
    • 158 °C
    • 415 °F

    Flash point

    • 199.81 ˚C est.

    Solubility expt.

    • Miscible (NIOSH, 2024)
    • Soluble in water, alcohol; soluble in 8 volumes of 3:1 ether:alcohol mixture
    • Soluble in ethanol
    • 548 g/100 g water at 20 °C
    • 1000 mg/mL
    • Solubility in water: miscible
    • Solubility in water: very soluble
    • Miscible

  • Synonyms

    • Phosphoric acid
    • 7664-38-2
    • ORTHOPHOSPHORIC ACID
    • o-Phosphoric acid
    • Wc-reiniger
    • Acidum phosphoricum
    • Sonac
    • Phosphorsaeure
    • Evits
    • Acide phosphorique
    • Phosphoricum acidum
    • Acido fosforico
    • Phosphorsaeureloesungen
    • Fosforzuuroplossingen
    • Vococid
    • White phosphoric acid
    • Phosphoric acid, ortho-
    • FEMA No. 2900
    • Amberphos 54
    • Superphosphoric acid
    • ortho-phosphoric acid
    • CCRIS 2949
    • HSDB 1187
    • trihydroxidooxidophosphorus
    • EINECS 231-633-2
    • H3PO4
    • UNII-E4GA8884NN
    • NSC 80804
    • NSC-80804
    • EPA Pesticide Chemical Code 076001
    • E4GA8884NN
    • DTXSID5024263
    • tetraoxophosphoric acid
    • CHEBI:26078
    • Phosphoric acid [NF]
    • INS-338
    • MFCD00011340
    • Y-11A06
    • UN1805
    • DTXCID804263
    • INS NO.338
    • E 338
    • E-338
    • trihydrogen tetraoxophosphate(3-)
    • EC 231-633-2
    • NSC80804
    • Phosphoric acid (NF)
    • NCGC00091005-01
    • E338
    • Oleth-4 phosphate
    • PHOSPHORIC ACID (II)
    • PHOSPHORIC ACID [II]
    • PHOSPHORIC ACID (MART.)
    • PHOSPHORIC ACID [MART.]
    • (PO(OH)3)
    • [PO(OH)3]
    • Caswell No. 662
    • Phosphoric acid 75%
    • PHOSPHORIC ACID (USP-RS)
    • PHOSPHORIC ACID [USP-RS]
    • K-etchant
    • Acido fosforico [Italian]
    • Acide phosphorique [French]
    • Fosforzuuroplossingen [Dutch]
    • CAS-7664-38-2
    • Phosphorsaeureloesungen [German]
    • Phosphoric acid 85%
    • Phosphoric acid, ACS reagent, >=85 wt. % in H2O
    • Phosphoric acid (aqueous)
    • Phospholeum
    • NaturasilAcne
    • phosphoric cid
    • Ortho-phosphate
    • phosphor-ic acid
    • NFB Orthophosphate
    • 2HP
    • NaturasilBite Relief
    • Orthophosphate(3-)
    • KEFO
    • ortho phosphoric acid
    • Phosphate ion(3-)
    • 62046-92-8
    • Phosphate anion(3-)
    • MIKRO KLENE DF
    • Phosphoricum acidum 6C
    • NaturasilCherry Angiomas
    • Phosphate (PO43-)
    • Phosphoric acid, 75%
    • Phosphoric acid, 85%
    • Orthophosphate (PO43-)
    • Phosphoric acid ion(3-)
    • Phosphoricum acidum 200C
    • Phosphate ion (PO43-)
    • SPA 2 (CATALYST)
    • CHEMBL1187
    • Phosphoric acid, 10% v/v
    • Phosphoric acid, Crystalline
    • SPA 2
    • PHOSPHORIC ACID [MI]
    • PHOSPHORIC ACID [FCC]
    • Phosphoricum Acidum Kit Refill
    • PHOSPHORIC ACID [FHFI]
    • PHOSPHORIC ACID [HSDB]
    • DECON 4512
    • PHOSPHORIC ACID [VANDF]
    • PHOSPHORIC ACID, AQUEOUS
    • Phosphoric acid, AR, >=88%
    • Phosphoric acid, technical grade
    • BDBM14671
    • CHEBI:52641
    • H3 P O4
    • PHOSPHORIC ACID [WHO-DD]
    • C 134 (ACID)
    • C 434 (ACID)
    • Phosphoric acid, AR, 88-93%
    • Phosphoric acid, LR, 88-93%
    • PHOSPHORICUM ACIDUM [HPUS]
    • Phosphoric acid, 85%, ACS grade
    • Phosphoric acid, puriss., >=99%
    • Phosphoric acid, 85%, HPLC grade
    • Tox21_111053
    • Tox21_202285
    • Tox21_303246
    • Phosphoric acid, ACS reagent, 85%
    • PHOSPHORIC ACID [ORANGE BOOK]
    • Phosphoric acid, for HPLC, >=85%
    • AKOS028109726
    • DB09394

  • Applications

    Phosphoric Acid (CAS 7664-38-2) is primarily used as a source of phosphate for fertilizer production (for example, monoammonium phosphate and diammonium phosphate). It is also used in metal surface treatment through phosphating processes to form phosphate coatings that improve corrosion resistance and prepare surfaces for coatings. In cleaning and descaling applications, phosphoric acid appears in solutions for rust removal and metal cleaning. In the food and beverage sector, it serves as an acidulant and acidity regulator (E338) to adjust pH and stabilize flavors. In electronics and metal manufacturing, it is used for surface cleaning and pretreatment of metals prior to processing or coating. It can also function as a pH adjuster or intermediate in the synthesis of phosphate-containing compounds, subject to local regulations and formulation limits.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 389.76
    methanol 759.02
    isopropanol 302.71
    water 1804.49
    ethyl acetate 19.66
    n-propanol 225.29
    acetone 194.77
    n-butanol 130.92
    acetonitrile 65.96
    DMF 840.78
    toluene 9.51
    isobutanol 122.74
    1,4-dioxane 107.38
    methyl acetate 36.49
    THF 269.72
    2-butanone 49.62
    n-pentanol 85.17
    sec-butanol 117.41
    n-hexane 11.61
    ethylene glycol 551.84
    NMP 244.14
    cyclohexane 11.97
    DMSO 568.94
    n-butyl acetate 20.08
    n-octanol 26.07
    chloroform 8.66
    n-propyl acetate 22.56
    acetic acid 140.51
    dichloromethane 13.1
    cyclohexanone 43.58
    propylene glycol 398.19
    isopropyl acetate 18.0
    DMAc 312.21
    2-ethoxyethanol 247.15
    isopentanol 73.15
    n-heptane 11.81
    ethyl formate 49.16
    1,2-dichloroethane 16.59
    n-hexanol 59.66
    2-methoxyethanol 498.65
    isobutyl acetate 13.03
    tetrachloromethane 6.91
    n-pentyl acetate 16.21
    transcutol 99.32
    n-heptanol 40.92
    ethylbenzene 5.31
    MIBK 30.5
    2-propoxyethanol 195.56
    tert-butanol 194.57
    MTBE 39.15
    2-butoxyethanol 107.23
    propionic acid 89.37
    o-xylene 10.07
    formic acid 370.18
    diethyl ether 52.36
    m-xylene 9.98
    p-xylene 6.77
    chlorobenzene 3.69
    dimethyl carbonate 57.17
    n-octane 4.3
    formamide 492.12
    cyclopentanone 99.68
    2-pentanone 45.05
    anisole 17.24
    cyclopentyl methyl ether 64.36
    gamma-butyrolactone 92.13
    1-methoxy-2-propanol 336.52
    pyridine 35.06
    3-pentanone 28.16
    furfural 77.26
    n-dodecane 2.42
    diethylene glycol 261.47
    diisopropyl ether 15.66
    tert-amyl alcohol 84.66
    acetylacetone 42.67
    n-hexadecane 2.48
    acetophenone 17.75
    methyl propionate 38.86
    isopentyl acetate 13.84
    trichloroethylene 10.76
    n-nonanol 22.68
    cyclohexanol 58.01
    benzyl alcohol 29.03
    2-ethylhexanol 20.13
    isooctanol 25.03
    dipropyl ether 40.84
    1,2-dichlorobenzene 3.58
    ethyl lactate 45.3
    propylene carbonate 32.22
    n-methylformamide 398.6
    2-pentanol 72.29
    n-pentane 17.31
    1-propoxy-2-propanol 112.9
    1-methoxy-2-propyl acetate 31.64
    2-(2-methoxypropoxy) propanol 48.1
    mesitylene 8.81
    ε-caprolactone 33.17
    p-cymene 6.34
    epichlorohydrin 64.19
    1,1,1-trichloroethane 7.47
    2-aminoethanol 563.69
    morpholine-4-carbaldehyde 202.44
    sulfolane 130.72
    2,2,4-trimethylpentane 3.96
    2-methyltetrahydrofuran 73.77
    n-hexyl acetate 16.14
    isooctane 4.01
    2-(2-butoxyethoxy)ethanol 72.16
    sec-butyl acetate 11.71
    tert-butyl acetate 20.92
    decalin 3.15
    glycerin 533.92
    diglyme 133.1
    acrylic acid 99.74
    isopropyl myristate 8.76
    n-butyric acid 56.87
    acetyl acetate 12.4
    di(2-ethylhexyl) phthalate 11.46
    ethyl propionate 20.74
    nitromethane 157.43
    1,2-diethoxyethane 28.32
    benzonitrile 12.72
    trioctyl phosphate 12.36
    1-bromopropane 10.99
    gamma-valerolactone 117.33
    n-decanol 17.38
    triethyl phosphate 13.53
    4-methyl-2-pentanol 34.47
    propionitrile 41.48
    vinylene carbonate 27.39
    1,1,2-trichlorotrifluoroethane 77.5
    DMS 15.08
    cumene 5.58
    2-octanol 21.59
    2-hexanone 28.25
    octyl acetate 12.57
    limonene 8.27
    1,2-dimethoxyethane 213.75
    ethyl orthosilicate 14.19
    tributyl phosphate 10.89
    diacetone alcohol 60.63
    N,N-dimethylaniline 25.88
    acrylonitrile 54.97
    aniline 29.05
    1,3-propanediol 337.67
    bromobenzene 2.24
    dibromomethane 9.32
    1,1,2,2-tetrachloroethane 13.85
    2-methyl-cyclohexyl acetate 13.33
    tetrabutyl urea 21.48
    diisobutyl methanol 15.04
    2-phenylethanol 25.36
    styrene 5.16
    dioctyl adipate 12.79
    dimethyl sulfate 81.93
    ethyl butyrate 18.11
    methyl lactate 93.33
    butyl lactate 30.28
    diethyl carbonate 12.99
    propanediol butyl ether 87.98
    triethyl orthoformate 18.97
    p-tert-butyltoluene 7.19
    methyl 4-tert-butylbenzoate 28.29
    morpholine 178.91
    tert-butylamine 104.71
    n-dodecanol 13.63
    dimethoxymethane 316.64
    ethylene carbonate 27.49
    cyrene 63.61
    2-ethoxyethyl acetate 18.9
    2-ethylhexyl acetate 10.43
    1,2,4-trichlorobenzene 4.42
    4-methylpyridine 28.16
    dibutyl ether 12.8
    2,6-dimethyl-4-heptanol 15.04
    DEF 72.8
    dimethyl isosorbide 64.97
    tetrachloroethylene 13.14
    eugenol 42.66
    triacetin 18.23
    span 80 43.47
    1,4-butanediol 188.78
    1,1-dichloroethane 11.87
    2-methyl-1-pentanol 37.16
    methyl formate 230.19
    2-methyl-1-butanol 66.77
    n-decane 3.66
    butyronitrile 37.13
    3,7-dimethyl-1-octanol 14.61
    1-chlorooctane 5.98
    1-chlorotetradecane 3.31
    n-nonane 3.89
    undecane 2.87
    tert-butylcyclohexane 3.16
    cyclooctane 5.9
    cyclopentanol 128.26
    tetrahydropyran 62.26
    tert-amyl methyl ether 28.89
    2,5,8-trioxanonane 95.6
    1-hexene 16.82
    2-isopropoxyethanol 118.57
    2,2,2-trifluoroethanol 113.5
    methyl butyrate 28.53

    Scent© AI

1 4

IFRA standard 51

Recommendation
No restriction
Maximum acceptable concentrations in the finished product (%)
Category 1
Products applied to the lips
 No restriction Category 7A
Rinse-off products applied to the hair with some hand contact
 No restriction
Category 2
Products applied to the axillae
 No restriction Category 7B
Leave-on products applied to the hair with some hand contact
 No restriction
Category 3
Products applied to the face/body using fingertips
 No restriction Category 8
Products with significant anogenital exposure
 No restriction
Category 4
Products related to fine fragrance
 No restriction Category 9
Products with body and hand exposure, primarily rinse off
 No restriction
Category 5A
Body lotion products applied to the body using the hands (palms), primarily leave on
 No restriction Category 10A
Household care products with mostly hand contact
 No restriction
Category 5B
Face moisturizer products applied to the face using the hands (palms), primarily leave on
 No restriction Category 10B
Household care products with mostly hand contact, including aerosol/spray products (with potential leave-on skin contact)
 No restriction
Category 5C
Hand cream products applied to the hands using the hands (palms), primarily leave on
 No restriction Category 11A
Products with intended skin contact but minimal transfer of fragrance to skin from inert substrate without UV exposure
 No restriction
Category 5D
Baby Creams, baby Oils and baby talc
 No restriction Category 11B
Products with intended skin contact but minimal transfer of fragrance to skin from inert substrate with potential UV exposure
 No restriction
Category 6
Products with oral and lip exposure
 No restriction Category 12
Products not intended for direct skin contact, minimal or insignificant transfer to skin
 No restriction