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Description

Mercury (I) sulfate, Hg2SO4, is a sparingly soluble salt of monovalent mercury. The practical value of the product is related to electrochemistry: the Hg/Hg2SO4 pair in a solution of potassium sulfate provides a reference electrode without chloride ions, and a paste of mercuric sulfate with mercury serves as a depolarizer in normal Weston and Clark cells.

Basic Attributes

• CAS No.: 7783-36-0
• Formula on the card: H2O4S,2Hg (Hg2SO4)
• Molecular weight: 497.24
• Exact weight: 499.89300
• EU number: 231-993-0
• UNII:PI950N9DYS
• UN number: 1645
• DSSTox ID: DTXSID9074565
• HS code: 28521000
• PSA Specifications: 88.64000
• XLogP3: -0.26220
• RTECS number: OX0480000
• EPA Hazardous Waste Number: D009 (mercury)

Physico-chemical characteristics

• Color and form: white to slightly yellow crystalline powder; colorless monoclinic crystals
• Appearance of commercial form: white, pale yellow or beige powder
• Density: 7.56 g/cm3
• Melting point: decomposes [AES93]
• Solubility in water: 0.05 g per 100 g H2O [KIR81]; practically insoluble
• Acid solubility: soluble in dilute nitric acid [MER06]
• Experimental properties: photosensitive
• Flammability characteristics: non-flammable; When heated, it decomposes, releasing toxic mercury vapor.
• Reactive group: metals, less reactive

Scope of application

• Weston's normal cell: a paste of mercury (I) sulfate with mercury forms a depolarizer and cathode part, the electrolyte is a saturated solution of cadmium sulfate; the element provides a stable voltage and from 1911 to 1990 served as an international standard for EMF
• Clark's normal element: the same salt paired with zinc sulfate
• mercury-sulfate comparison electrode Hg/Hg2SO4 with a saturated solution of potassium sulfate - used where the chloride ion in the electrolyte is unacceptable: electrical analysis, battery testing, corrosion research
• preparative chemistry: preparation of other mercury compounds

Toxicity and exposure limits

• LD50 oral, rat: 205 mg/kg
• LD50 oral, mouse: 152 mg/kg
• OSHA standard (repealed in 1989, continues to apply in some states): mercury vapor - TWA 0.05 mg/cu. m, marked “leather”; non-alkyl compounds - ceiling value 0.1 mg/cu. m, "skin"
• NIOSH Guidelines: Exposure Limit 0.05 mg/cc. m as a weighted average over 10 hours, “skin” (mercury vapor); ceiling value 0.1 mg/cu. m, “skin” (mercury compounds, except organoalkyl)

Safety Information

• Hazard statements: H300 + H310 + H330, H373, H410
• GHS classification: hazardous, H300 (100%) - fatal if swallowed; aggregated data of 39 companies from 2 notifications to the C&L ECHA register
• Precautions: P260, P262, P264, P270, P271, P273, P280, P284, P301 + P310, P302 + P350, P302 + P352 + P310, P304 + P340, P310, P314, P320, P321, P322, P330, P361, P363, P391, P403 + P233, P405, P501
• Tags: T+, N
• Packaging level: II; hazard category: 6.1(a)
• Transport codes: UN 1645, 6.1/page. 2
• WGK Germany: 3
• Hazard class code: 26/27/28-33-50/53
• Safety instructions: 13-28-45-60-61

Storage, protective equipment, emergency measures

The warehouse is ventilated, low temperature, dry; storage and transportation separately from food products. Protective equipment: chemically resistant gloves, shoes, safety glasses; when extinguishing a fire - a self-contained breathing apparatus with positive pressure and a chemical protective suit recommended by the manufacturer (protective clothing for firefighters in the event of a spill is ineffective). The premises are ventilated, the floors are made non-porous, containers with mercury compounds are kept tightly closed and regularly treated with a diluted solution of calcium sulfide; staff shower at the end of their shift.

Emergency procedures according to ERG 151 (toxic substances, non-flammable): containment of an area of ​​at least 25 m (75 ft) for solids and 50 m (150 ft) for liquids, for a fire involving a tank, wagon or tanker - containment and evacuation to 800 m (1/2 mile) (ERG, 2016). Do not allow material into water bodies, sewers, basements and enclosed spaces, cover with film, cover with dry non-flammable sorbent and transfer to containers; Do not supply water inside containers. Spilled mercury is removed with a special vacuum cleaner, the area is washed with a dilute solution of calcium sulfide, and small amounts are bound with copper granules.

Purification of wastewater from mercury: BMS process - wastewater is chlorinated, mercury is oxidized to an ionic form and collected on an adsorbent (activated carbon with sulfur concentrate on the surface), the spent adsorbent is distilled off to extract mercury; TMR IMAC process - oxidation with excess chlorine followed by absorption of mercury ions by ion exchange resin and desorption with hydrochloric acid solution.

Disposal: Generators of waste containing 100 kg or more of this contaminant per month (EPA hazardous waste number D009) are required to comply with USEPA regulations for storage, transport, handling and disposal. Solid wastes containing mercury are tested using the toxic leach procedure (40 CFR 261.24) and, if positive, are treated as hazardous under RCRA. Transportation is permitted only if the sender is registered and the cargo is properly classified, packaged, and labeled in accordance with 49 CFR 171-177; For air transport, IATA rules apply (resolutions 618 and 619); for maritime transport, the International Maritime Dangerous Goods Code applies.