Description
Zinc chloride is a white deliquescent salt. It forms acidic solutions in water and in polar organic solvents such as ethanol, acetone, and ether. Anhydrous zinc chloride hydrolyzes with moisture to form hydrochloric acid. It also forms complex ions with water, ammonia, and some organic solvents.
Zinc chloride reacts with sulphide to minimise release of H2S gas in waste treatment facilities. Zinc chloride 50% solution also serves as a high-quality mercerising agent for cotton. Zinc chloride is incompatible with strong oxidising agents, moisture, cyanides, sulphides, and potassium.
Chemical Properties
Zinc chloride typically appears as white, deliquescent, hexagonal crystals or as a colorless solution. Its fumes consist of white particulate matter dispersed in air. A 10% aqueous solution is acidic to litmus. It is soluble in water, alcohol, glycerol, and ether.
Physical properties
White crystalline powder or granules; hygroscopic; density 2.907 g/cm
3; melts at 290°C; vaporizes at 732°C; vapor pressure 1 torr at 428°C and 20 torrat 536°C; highly soluble in water, 432 g/100mL at 25°C; aqueous solution acidic in litmus test; also soluble in ethanol, glycerol, and acetone.
Uses
Zinc chloride is used as an organic catalyst. It is deliquescent, which
makes it an excellent dehydrating and drying agent. It is used in electroplating other metals,
as an antiseptic, as a component of some deodorants, and as an astringent. It is also used for
fireproofing materials and as a food preservative. Zinc chloride is also used in embalming and
taxidermy fluids.
Uses
Zinc chloride is used as a wood preservative and in fireproofing timber. Other uses are as a deodorant in disinfecting fluids; in dental cements; in electroplating; in etching metals and glass; as flux for soldering; as a mordant in printing and dyeing textiles; in making dry batteries; in denaturing alcohols; in vulcanizing rubber; in manufacturing parchment; in making artificial silk; in making activated carbon and cold-water glues; and in refining petroleum. Also, zinc chloride is used as a dehydrating and condensing agent in organic syntheses. In medicine it is used as an astringent and antiseptic.
Preparation
Zinc chloride is prepared by the reaction of zinc oxide or zinc metal with dilute hydrochloric acid, followed by crystallization:
ZnO + 2HCl → ZnCl2 + H2O
Zn + 2HCl → ZnCl2 + H2
Definition
ChEBI: A compound of zinc and chloride ions in the ratio 1:2. It exists in four crystalline forms, in each of which the Zn2+ ions are trigonal planar coordinated to four chloride ions.
Definition
zinc chloride: A white crystalline compound, ZnCl
2. The anhydrous salt, which is deliquescent, can be made by the action of hydrogen chloride gas on hot zinc; r.d. 2.9; m.p. 283°C; b.p. 732°C. It has a relatively low melting point and sublimes easily, indicating that it is a molecular compound rather than ionic. Various hydrates also exist. Zinc chloride is used as a catalyst, dehydrating agent, and Ûux for hard solder. It was once known as butter of zinc.
General Description
Zinc chloride is a colorless liquid. Zinc chloride is mildly corrosive to metals. Zinc chloride causes burns to eyes, skin and mucous membranes.
Air & Water Reactions
When dissolved in water, Zinc chloride is a strong acid. [Handling Chemicals Safely 1980. p. 964]
Reactivity Profile
Acidic salts, such as ZINC CHLORIDE, are generally soluble in water. The resulting solutions contain moderate concentrations of hydrogen ions and have pH's of less than 7.0. They react as acids to neutralize bases. These neutralizations generate heat, but less or far less than is generated by neutralization of inorganic acids, inorganic oxoacids, and carboxylic acid. They usually do not react as either oxidizing agents or reducing agents but such behavior is not impossible. Many of these compounds catalyze organic reactions.
Hazard
Inhalation of zinc chloride fumes can injure lungs and respiratory tract. Dusts or fumes also cause dermatitis, boils, conjunctivitis, and gastrointestinal tract upset (Lewis(Sr), R.J. 1996. Sax’s Dangerous Properties of Industrial Materials, 9th ed. New York: Van Nostrand Reinhold). LD
50 oral (rat): 350mg/kg LCLO (inhalation): 1.960 g/m
3/10 min.
Health Hazard
Solid or water solution is astringent and can irritate the eyes. When ingested, can cause intoxication, severe irritation of stomach, nausea, vomiting, and diarrhea.
Health Hazard
Exposures to zinc chloride cause adverse health effects and poisoning. On contact with the skin, zinc chloride causes skin burns and ulcerations, redness, eyes develop pain and blurred vision, and any splashes from solutions may cause eye damage. It is extremely
destructive to the tissues of the mucous membranes and upper respiratory tract. The
symptoms of toxicity include, but are not limited to, burning sensation, coughing, wheezing, laryngitis, shortness of breath, headache, nausea and vomiting, and irritation or corrosion to the gastrointestinal tract with abdominal pain. After repeated exposures of zinc
chloride through skin contact, occupational workers develop varying degrees of skin
problems, such as dermatitis and skin ulcerations. Repeated inhalation of zinc chloride
causes occupational asthma among workers
Fire Hazard
Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.
reaction suitability
reagent type: catalyst
core: zinc
Safety Profile
Poison by ingestion,
intravenous, and intraperitoneal routes.
Human systemic effects by inhalation: pulm-
onary changes. An experimental teratogen.
Experimental reproductive effects.
Questionable carcinogen with experimental tumorigenic data. Human mutation data
reported. A corrosive irritant to skin, eyes,
and mucous membranes, Exposure to ZnCl2
fumes or dusts can cause dermatitis, boils,
conjunctivitis, gastrointestinal tract upsets.
The fumes are highly toxic. Incompatible
with potassium. Mixtures of the powdered
chloride and powdered zinc are flammable.
When heated to decomposition it emits
toxic fumes of Cland ZnO. See also ZINC
COMPOUNDS and CHLORIDES.
Potential Exposure
Zinc chloride is used in iron galvanizing;
as a wood preservative; for dry battery cells; as a soldering
flux; in textile finishing; in vulcanized fiber;
reclaiming rubber; in oil and gas well operations; oil refining;
manufacturing of parchment paper; in dyes; activated
carbon; in chemical synthesis; in adhesives; dentists’
cement; deodorants, disinfecting and embalming solutions;
and taxidermy. It is also produced by military screeningsmoke.
Shipping
UN2331 Zinc chloride, anhydrous, Hazard class: 8;
Labels: 8-Corrosive material. UN1840 Zinc chloride, solution,
Hazard class: 8; Labels: 8-Corrosive material.
Purification Methods
The anhydrous material can be sublimed under a stream of dry HCl, followed by heating to 400o in a stream of dry N2. It sublimes at high vacuum. Also purify it by refluxing (50g) in dioxane (400mL) with 5g zinc dust, filtering hot and cooling to precipitate ZnCl2. Crystallise it from dioxane and store it in a desiccator over P2O5. It has also been dried by refluxing in thionyl chloride. [Weberg et al. J Am Chem Soc 108 6242 1986.] Hygroscopic: minimal exposure to the atmosphere is necessary. [Wagenknecht & Juza Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol II p 1070 1965.]
Incompatibilities
Aqueous solutions are strongly acidic.
Incompatible with bases and potassium. Incompatible with
strong oxidizers (chlorates, nitrates, peroxides, permanganates,
perchlorates, chlorine, bromine, fluorine, etc.); contact
may cause fires or explosions. Keep away from
alkaline materials, strong bases, strong acids, oxoacids,
epoxides. Corrosive to metals.
Waste Disposal
Dump in water; add soda ash
and stir, then neutralize and flush to sewer with water.
Alternatively, zinc chloride may be recovered from spent
catalysts and used in acrylic fiber spinning solutions.
Precautions
Exposures to zinc chloride are dangerous, corrosive, and cause burns to any area of contact. Harmful if swallowed or inhaled. Affects the cardiovascular system.
