Chemical elements
  Zinc
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
      Zinc Fluoride
      Zinc Chloride
      Zinc Oxychlorides
      Zinc Bromide
      Zinc Iodide
      Zinc Hypochlorite
      Zinc Perchlorate
      Zinc Bromate
      Zinc Iodate
      Zinc Periodate
      Zinc Oxide
      Zinc Hydroxide
      Zincates
      Zinc Peroxide
      Zinc Sulphide
      Zinc Hydrosulphite
      Zinc Thiosulphate
      Zinc Sulphite
      Zinc Sulphate
      Zinc Dithionate
      Zinc Tetrathionate
      Zinc Pentathionate
      Zinc Selenide
      Zinc Selenites
      Zinc Selenate
      Zinc Telluride
      Zinc Tellurate
      Zinc Chromite
      Zinc Chromate
      Zinc Dichromate
      Zinc Molybdate
      Zinc Tungstate
      Zinc Nitride
      Zinc Azide
      Zinc Amide
      Zinc Ammoniate
      Zinc Nitrite
      Zinc Nitrate
      Basic Zinc Nitrates
      Zinc Phosphide
      Zinc Hydrophosphide
      Zinc Hypophosphite
      Zinc Phosphite
      Zinc Thiophosphite
      Zinc Orthophosphate
      Zinc Pyrophosphate
      Ammonium Zinc Orthophosphate
      Zinc Thiophosphates
      Zinc Arsenide
      Zinc Arsenite
      Zinc Arsenates
      Zinc Metantimonate
      Thioantimony Salts of Zinc
      Zinc Carbonate
      Zinc Thiocarbonate
      Zinc Cyanide
      Zinc Thiocyanate
      Zinc Silicide
      Zinc Silicates
      Zinc Borates
      Zinc Perborate
    PDB 12ca-1ai0
    PDB 1aiy-1b6z
    PDB 1b71-1bs8
    PDB 1bsk-1cao
    PDB 1caq-1ctt
    PDB 1ctu-1de6
    PDB 1def-1dy0
    PDB 1dy1-1ed6
    PDB 1ed8-1exk
    PDB 1eyf-1fj9
    PDB 1fjg-1g0e
    PDB 1g0f-1gkq
    PDB 1gkr-1ha5
    PDB 1hbm-1hso
    PDB 1hsz-1i6v
    PDB 1i73-1im5
    PDB 1iml-1jcv
    PDB 1jcz-1jy8
    PDB 1jyb-1kh4
    PDB 1kh5-1kys
    PDB 1kzo-1llm
    PDB 1llu-1m7j
    PDB 1m9j-1mwo
    PDB 1mwq-1ndv
    PDB 1ndw-1nyq
    PDB 1nyr-1os4
    PDB 1os9-1p9w
    PDB 1paa-1pud
    PDB 1pv8-1q9l
    PDB 1q9m-1qv6
    PDB 1qv7-1r6o
    PDB 1r79-1ro9
    PDB 1ror-1sfo
    PDB 1sg0-1t3k
    PDB 1t4k-1tkh
    PDB 1tkj-1u0l
    PDB 1u10-1ums
    PDB 1umt-1v67
    PDB 1v6g-1vrq
    PDB 1vs0-1wew
    PDB 1wfe-1wwf
    PDB 1wwg-1xb1
    PDB 1xb8-1xpz
    PDB 1xq0-1y5w
    PDB 1y5x-1ylk
    PDB 1ylo-1z8r
    PDB 1z93-1zkx
    PDB 1zl6-258l
    PDB 2a03-2afo
    PDB 2afs-2atq
    PDB 2au3-2bfz
    PDB 2bg2-2c3a
    PDB 2c4r-2cij
    PDB 2cim-2czr
    PDB 2d0w-2djw
    PDB 2dkc-2e1b
    PDB 2e1s-2eer
    PDB 2eex-2em4
    PDB 2em5-2eoj
    PDB 2eok-2erq
    PDB 2esf-2fa7
    PDB 2fac-2fpx
    PDB 2fqp-2g84
    PDB 2g87-2gvf
    PDB 2gvi-2han
    PDB 2hap-2huc
    PDB 2hue-2imc
    PDB 2imr-2j65
    PDB 2j6a-2jq5
    PDB 2jr7-2kfn
    PDB 2kft-2l75
    PDB 2lgv-2nx9
    PDB 2nxa-2oc8
    PDB 2occ-2osm
    PDB 2oso-2p53
    PDB 2p57-2pow
    PDB 2ppb-2q8j
    PDB 2qa1-2qp6
    PDB 2qpj-2r71
    PDB 2r74-2sod
    PDB 2srt-2v86
    PDB 2v87-2vp7
    PDB 2vpb-2vyo
    PDB 2vz5-2wey
    PDB 2wfq-2wx0
    PDB 2wx1-2xam
    PDB 2xan-2xr9
    PDB 2xrg-2ytd
    PDB 2yte-2z30
    PDB 2z3g-2zet
    PDB 2zh0-3a32
    PDB 3a36-3aoi
    PDB 3at1-3bk1
    PDB 3bk2-3byr
    PDB 3byw-3cia
    PDB 3ciz-3d08
    PDB 3d09-3dbu
    PDB 3dc3-3dp6
    PDB 3dpe-3e1w
    PDB 3e1z-3ebh
    PDB 3ebi-3epk
    PDB 3epl-3f28
    PDB 3f2b-3fhe
    PDB 3fhp-3ful
    PDB 3fum-3g9y
    PDB 3ga3-3gpu
    PDB 3gpx-3h2w
    PDB 3h3e-3hfy
    PDB 3hgz-3hsn
    PDB 3hso-3i8v
    PDB 3i9b-3ij6
    PDB 3ijf-3ixe
    PDB 3iz0-3k34
    PDB 3k35-3kiy
    PDB 3kj1-3kvt
    PDB 3kwa-3lat
    PDB 3lcn-3lrr
    PDB 3ls1-3m1n
    PDB 3m1v-3mek
    PDB 3men-3mru
    PDB 3ms0-3n63
    PDB 3n64-3nin
    PDB 3nis-3ny2
    PDB 3ny3-3ohc
    PDB 3ohd-3oyl
    PDB 3oym-3pih
    PDB 3pki-3r0d
    PDB 3rj7-3t74
    PDB 3t87-3u9g
    PDB 3ua7-3v24
    PDB 3v25-4agl
    PDB 4agm-4dih
    PDB 4dii-4efs
    PDB 4eg2-4fc8
    PDB 4fgm-6tli
    PDB 6tmn-9nse

Zinc Chloride, ZnCl2






The pure anhydrous salt of Zinc Chloride, ZnCl2, has been prepared by heating 3NH4Cl.ZnCl2 in a current of dry hydrogen chloride. The anhydrous salt has also been prepared by distilling anhydrous zinc sulphate with sodium or calcium chloride, by the action of heated zinc vapour and hydrogen on barium chloride, by distilling zinc with mercuric chloride, and by the action of chlorine on zinc oxide. Hydrous zinc chloride partially decomposes on heating, but the anhydrous salt may be obtained from it by treatment with concentrated hydrochloric acid and evaporation in an atmosphere of hydrogen chloride. It may also be prepared by adding zinc to molten lead chloride, passing dry chlorine into fused zinc, or by fusing zinc bromide in an atmosphere of chlorine.

Commercially, the salt is obtained anhydrous by distilling a mixture of zinc sulphate and sodium chloride, and in solution by dissolving zinc scraps, zinc blende, or zinc oxide in hydrochloric acid.

Anhydrous zinc chloride is white or greyish white, and derives its name, " butter of zinc," from its waxlike consistency. It is very hygroscopic, and the density of the fused salt at 25° C. is 2.907 (compared with water at 4° C.). It sublimes in chlorine to needle-shaped crystals that melt at 365° C, and boil at 730° C.

The solubility of zinc chloride has been given as 78.5 parts ZnCl2 in 100 parts of solution, but the equilibrium curves between ZnCl2 and water are difficult to interpret.

It is strongly dissociated in aqueous solution, though the anion ZnCr appears to be present in considerable concentration even in solutions more dilute than 0.1 molar. It is only hydrolysed slightly, and, according to Vogel, hydrous zinc chloride can be converted into the anhydrous by evaporation under about 20 inches of mercury, though water, especially at higher temperatures and concentrations, tends to form basic compounds.

Zinc chloride is soluble in many organic solvents, including alcohol, and combines with a number of organic compounds. It is indefinitely soluble in glycerine.

Nitrosyl chloride acts upon zinc to form pale yellow ZnCl2.NOCl, which is unstable under ordinary conditions.

The formula ZnCl2 is indicated by the vapour density, the freezing- points of solutions in urethane, and the boiling-points of quinoline solutions.

Molten zinc chloride conducts electricity well, and pure zinc separates at the cathode on electrolysis.

The specific heat of the fused salt is 0.13618.

Anhydrous zinc chloride is poisonous, and is used industrially for impregnating wood, for preserving animal stuffs, in the manufacture of parchment paper, for weighting cotton goods, in the dye industry, and as a disinfectant. It is also employed as a caustic in surgery and as a dehydrating reagent in many organic reactions. Its solution in water, since it destroys organic substances, is used for cleansing and as a flux in soldering.

[Zn] + (Cl2) = [ZnCl2]+97.140 Cal.

[ZnCl2] + Aq. = ZnCl2.Aq. + 15.220 Cal. (+9.767 Cal. in alcohol).

According to Mylius and Dietz, zinc chloride can crystallise out with 1 or l½ or 2½ or 3 or 4 molecules of water.

The trihydrate, ZnCl2.3H2O, separates in large crystals, when a solution containing 70.5 per cent. ZnCl2 is cooled for twenty-four hours at 0° C. The crystals are hygroscopic rhombic tablets that begin to melt at 4° or 5° C., and form a homogeneous liquid at 9° C.

The needles of a dihydrate said to be obtained by cooling a saturated solution to -20° C. are doubtful.

The hydrate, ZnCl2.l½H2O, was obtained in bulky crystals by evaporating a solution of zinc chloride over phosphorus pentoxide.

A bluish-white mass of zincoso-zincic chloride, Zn3Cl5, results from the solution of metallic zinc in molten zinc chloride. It is very hygroscopic, rapidly hydrolysed by water, and is probably best formulated as ZnCl.2ZnCl2.

Deliquescent rhombic crystals of the acid salt, 2ZnCl2.HCl.2H2O, separate from a solution of zinc chloride into which hydrogen chloride has been passed when the density of the liquid at 25° C. is 2. At 100° C. they lose HCl, and anhydrous ZnCl2 is in contact with a concentrated solution of the salt and hydrochloric acid. If this mother-liquor is treated with hydrogen chloride more crystals separate, and finally, if the liquid is saturated with hydrogen chloride and cooled to 0° C., long needles of ZnCl2.HCl.2H2O crystallise. These readily lose hydrogen chloride in dry air and form 2ZnCl2.HCl.2H2O.


Compounds of Zinc Chloride with Ammonia

The diammoniate ZnCl2.2NH4 is formed in the active Leclanche cell. It can be prepared by passing ammonia gas into an alcoholic solution of zinc chloride, or by passing ammonia into a hot concentrated aqueous solution of zinc chloride, and, after cooling to separate the less soluble tetrammoniate, ZnCl2.4NH4.H2O, crystallising the mother-liquor. The rhombic crystals are stable in air, insoluble in water or alcohol, and soluble in acids, ammonia, caustic alkalies, and ammonium chloride. Boiling water decomposes them. It can also be prepared by adding ammonia to cold dilute zinc chloride solution, by dissolving freshly precipitated zinc hydroxide in ammonium chloride, and by heating more highly ammoniated zinc chlorides. It distils when heated into glassy, hygroscopic monammoniate, ZnCl2.NH4.

The last named is very stable under heat, and is produced when ammonia acts on hot zinc chloride. Water decomposes it into ZnCl2.2NH4 and an oxychloride of zinc.

The more unstable tetrammoniate, ZnCl2.4NH4.H2O, and pentammoniate, ZnCl2.5NH4.H2O, have been prepared: the former in pearly leaflets by saturating an aqueous solution of zinc chloride with ammonia gas and cooling, the latter in octahedra by cooling a solution of zinc chloride in ammonia after passing ammonia gas. Isambert prepared ZnCl2.6NH4 and examined the heats of formation of the ammoni- ated zinc chlorides.

Various other compounds have been reported.

The hexammoniate ZnCl2.6NH4 is apparently formed when zinc chloride absorbs ammonia gas at -18° C. At ordinary temperatures less ammonia than corresponds to this formula is absorbed. It decomposes at 57.5° C. - at about 64.5° C. the tetrammoniate is formed, which decomposes at 92° C. and loses increasing quantities of ammonia as the temperature rises. At about 98° C. the composition of the residue approximates to ZnCl2.2NH4.

Double Dhlorides of Zinc

The following double chlorides of zinc have been described: LiCl.ZnCl2.3H2O and 2LiCl.ZnCl2.2H2O; 3LiCl.ZnCl2.10H2O may exist; 2NaCl.ZnCl2.3H2O; KCl.ZnCl2.2H2O and 2KCl.ZnCl2; 2NH4Cl.ZnCl2; 3NH4Cl.ZnCl2; 2RbCl.ZnCl2; 2CsCl.ZnCl2 and 3CsCl.ZnCl2Cl2; CaCl2.ZnCl2. 5½H2O and 2CaCl2.ZnCl2.6H2O; SrCl2.ZnCl9.4H2O and SrCl2.ZnCl2; BaCl2.ZnCl2.4H2O; MgCl2.ZnCl2.6H2O; ZnCl2. PtCl4.6H2O.
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