Phosphoric acid

Molecular Structure:

Molecular Formula: H₃PO₄
Molecular Weight: 97.99
IUPAC Name: Phosphoric acid
Synonyms of Phosphoric acid (CAS NO.7664-38-2): Acide phosphorique ; Acido fosforico ; Acidum phosphoricum ; Fosforzuuroplossingen ; Hydrogen phosphate ; Orthophosphoric acid ; Phosphoric acid, ortho- ; Phosphorsaeureloesungen ; o-Phosphoric acid
CAS NO: 7664-38-2
EINECS: 231-633-2
H bond acceptors: 4
H bond donors: 3
Freely Rotating Bonds: 0
Polar Surface Area: 54.57 Å²
Index of Refraction: 1.51
Molar Refractivity: 13.52 cm³
Molar Volume: 45.2 cm³
Surface Tension: 136.3 dyne/cm
Density: 2.168 g/cm³
Boiling Point: 158 °C at 760 mmHg
Vapour Pressure: 1.41 mmHg at 25°C
Melting point: ~40 °C
Solubility  H₂O: soluble
Color:  ≤10(APHA)
Water Solubility: MISCIBLE
Appearence: Clear liquid
Product Categories of Phosphoric acid (CAS NO.7664-38-2): INORGANIC & ORGANIC CHEMICALS;Inorganics;HPLC;HPLC Buffer;HPLC Buffers;HPLC Buffers - SolutionChromatography/CE Reagents;Solution;PAlphabetic;Analytical Standards;NMRStable Isotopes;P;PER - POLA;Spectroscopy;Alphabetical Listings;Flavors and Fragrances;O-P;Organic Phosphonates

 Phosphoric acid (CAS NO.7664-38-2) is used in many soft drinks (primarily cola), but it has been linked to lower bone density in epidemiological studies. Phosphoric acid is used in dentistry and orthodontics as an etching solution, to clean and roughen the surfaces of teeth where dental appliances or fillings will be placed. Besides, Phosphoric acid is also an ingredient in over-the-counter anti-nausea medications that also contain high levels of sugar (glucose and fructose). Further more this acid is also used in many teeth whiteners to eliminate plaque that may be on the teeth before application.

Production of Phosphoric acid (CAS NO.7664-38-2) includes three routes - the Thermal Process, the Wet Process and the dry Kiln Process.
Firstly let us introduce thermal phosphoric acid
This very pure phosphoric acid is obtained by burning elemental phosphorus to produce phosphorus pentoxide and dissolving the product in dilute phosphoric acid. Because most impurities present in the rock have been removed when extracting phosphorus from the rock in a furnace, this produces a very pure phosphoric acid. The end result is food-grade, thermal phosphoric acid; however, for critical applications, additional processing to remove arsenic compounds may be needed.

Secondly  let us introduce wet phosphoric acid
See also: Nitrophosphate process
Wet process phosphoric acid process: add sulfuric acid to tricalcium phosphate rock, typically found in nature as apatite.

The reaction is: Ca₅(PO₄)₃X + 5 H₂SO₄ + 2 H₂O → 3 H₃PO₄ + 5 CaSO₄ · 2 H₂O + HX
where X may include OH, F, Cl, and Br
The initial phosphoric acid solution may contain 23-33% P₂O₅, but can be concentrated by the evaporation of water to produce commercial- or merchant-grade phosphoric acid, which contains about 54% P₂O₅. Further evaporation of water yields superphosphoric acid with a P₂O₅ concentration above 70%.

Digestion of the phosphate ore using sulfuric acid yields the insoluble calcium sulfate (gypsum), which is filtered and removed as phosphogypsum. Wet-process acid can be furthered purified by removing fluorine to produce animal-grade phosphoric acid, or by solvent extraction and arsenic removal to produce food-grade phosphoric acid.

Finally let us introduce Kiln Phosphoric Acid
Kiln phosphoric acid (KPA) process technology is the most recent technology which will both make low grade phosphate rock reserves commercially viable and will increase the P₂O₅ recovery from existing phosphate reserves. This may significantly extend the commercial viability of phosphate reserves.

Community Right-To-Know List. Reported in EPA TSCA Inventory. EPA Genetic Toxicology Program.

Safety Information about 
Hazard Codes: CXnTF
Risk Statements: 34-35-22-39/23/24/25-36/38-11
R11: Highly flammable. 
R22: Harmful if swallowed. 
R34: Causes burns. 
R35: Causes severe burns. 
R36/38: Irritating to eyes and skin.
R39/23/24/25: Toxic: danger of very serious irreversible effects through inhalation, in contact with skin and if swallowed
Safety Statements: 7-16-26-45-36/37/39-1/2-24/25
S7: Keep container tightly closed. 
S16: Keep away from sources of ignition. 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S1/2: Keep locked up and out of the reach of children. 
S24/25: Avoid contact with skin and eyes. 
S36/37/39: Wear suitable protective clothing, gloves and eye/face protection.
RIDADR: UN 3453 8/PG 3
WGK Germany: 3
RTECS: TB6300000
F: 3-10
HazardClass: 8
PackingGroup: III
Human poison by ingestion. Moderately toxic by skin contact. A corrosive irritant to eyes, skin, and mucous membranes, and a systemic irritant by inhalation. A common air contaminant. A strong acid. Mixtures with nitromethane are explosive. Reacts with chlorides + stainless steel to form explosive hydrogen gas. Potentially violent reaction with sodium tetrahydroborate. Dangerous; when heated to decomposition it emits toxic fumes of PO_x.

OSHA PEL: TWA 1 mg/m³; STEL 3 mg/m³
ACGIH TLV: TWA 1 mg/m³; STEL 3 mg/m³
DOT Classification:  8; Label: Corrosive

For occupational chemical analysis use OSHA: #ID-111 or NIOSH: Acids, Inorganic, 7903.

General Information: As in any fire, wear a self-contained breathing apparatus in pressure-demand, MSHA/NIOSH (approved or equivalent), and full protective gear. Wear appropriate protective clothing to prevent contact with skin and eyes. Wear a self-contained breathing apparatus (SCBA) to prevent contact with thermal decomposition products. Substance is noncombustible.
Extinguishing Media: For small fires, use water spray, dry chemical, carbon dioxide or chemical foam. Use water spray to cool fire-exposed containers. Use water spray, dry chemical, carbon dioxide, or chemical foam.
Handling: Wash thoroughly after handling. Use only in a well-ventilated area. Do not breathe dust, vapor, mist, or gas. Do not get in eyes, on skin, or on clothing. Use only in a chemical fume hood.
Storage: Store in a tightly closed container. Store in a cool, dry, well-ventilated area away from incompatible substances. Corrosives area.