Periodic acid

Periodic acid
	Orthoperiodic acid
Names
	Other names Paraperiodic acid; Iodic(VII) acid; Hydrogen periodate;
Identifiers
CAS Number	10450-60-9 (orthoperiodic) ; 13444-71-8 (metaperiodic) ;
3D model (JSmol)	(orthoperiodic): Interactive image; (metaperiodic): Interactive image;
ChemSpider	23622 (orthoperiodic) ; 58684 (metaperiodic) ;
ECHA InfoCard	100.030.839
EC Number	236-585-6;
PubChem CID	65185 (metaperiodic);
UNII	AK1D44L87G ; D4B1481B2J (metaperiodic) ;
UN number	UN3085
CompTox Dashboard (EPA)	DTXSID10883144 ;
	InChI (orthoperiodic): InChI=I=1S/H5IO6/c2-1(3,4,5,6)7/h(H5,2,3,4,5,6,7) Key: TWLXDPFBEPBAQB-UHFFFAOYSA-N; (metaperiodic): InChI=1/HIO4/c2-1(3,4)5/h(H,2,3,4,5) Key: KHIWWQKSHDUIBK-UHFFFAOYAH;
	SMILES (orthoperiodic): OI(=O)(O)(O)(O)O; (metaperiodic): O[I+3]([O-])([O-])[O-];
Properties
Chemical formula	HIO4 (metaperiodic); H5IO6 (orthoperiodic)
Molar mass	190.91 g/mol (HIO4); 227.941 g/mol (H5IO6)
Appearance	Colourless crystals
Melting point	128.5 °C (263.3 °F; 401.6 K)
Solubility	soluble in water, alcohols
Acidity (pKa)	pKa1 = 3.29; pKa2 = 8.31; pKa3 = 11.60
Conjugate base	Periodate
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H271, H314, H372, H400
Precautionary statements	P210, P260, P273, P303+P361+P353, P305+P351+P338
NFPA 704 (fire diamond)	3 0 0 OX
Safety data sheet (SDS)	External MSDS
Related compounds
Other anions	Perchloric acid HClO4; Perbromic acid HBrO4; Permanganic acid HMnO4; Telluric acid Te(OH)6; Perxenic acid H4XeO6;
Other cations	Sodium periodate; Potassium periodate;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Periodic acid (/ˌpɜːraɪˈɒdɪk/ per-eye-OD-ik) is an oxoacid of iodine. It can exist in two forms: orthoperiodic acid, with the chemical formula H₅IO₆, and metaperiodic acid, which has the formula HIO₄. Periodic acids are colourless crystals. Periodic acid features iodine in the highest oxidation state of +7.

Periodic acid was discovered by Heinrich Gustav Magnus and C. F. Ammermüller in 1833.