UsesĬobalt(II) chloride is used in humidity indicator in weather instruments. Solid lubricant, dye mordant, catalyst, barometers, UsesĪbsorbent for ammonia, gas masks, electroplating, sympathetic inks, hygrometers, manufacture of vitamin B It is also of use in manufacturing solid lubricants, as anĪdditive to fertilizers, as a chemical reagent in laboratories, and as an absorbent in gas masks,Įlectroplating, and the manufacture of vitamin B12. It is also used as a dye mordant (to fix the dye to Itself can cause damage to red blood cells. UsesĬobalt chloride (CoCl2) is used to manufacture vitamin B12, even though the compound Physical propertiesīlue leaflets turns pink in moist air hygroscopic the dihydrate is violet blue crystal the hexahydrate is pink monoclinic crystal density 3.36, 2.48 and 1.92 g/cm3 for anhydrous salt, dihydrate and hexahydrate, respectively anhydrous salt melts at 740☌ and vaporizes at 1,049☌ vapor pressure 60 torr at 801☌ the hexahydrate decomposes at 87☌ the anhydrous salt and the hydrates are all soluble in water, ethanol, acetone, and ether the solubility of hydrates in water is greater than the anhydrous salt. (1) Blue, (2) ruby-red crystals.Soluble in water, alcohol, and acetone. Pale blue leaflets, turns pink upon exposure to moist air. The anhydrous compound also may be obtained by passing chlorine over cobalt powder. The solution on concentration and cooling forms crystals of hexahydrate which on heating with SOCl2 dehydrates to anhydrous cobalt(II) chloride.Īlternatively, the hexahydrate may be converted to anhydrous CoCl2 by dehydration in a stream of hydrogen chloride and dried in vacuum at 100–150☌. The vapor-phase co-reductions with other metal halides by hydrogen results in finely divided intermetallics with applications as structural materials or compounds with useful thermoelectric, magnetic, and oxidation-resistance properties.Ĭobalt(II) chloride is prepared by the action of cobalt metal or its oxide, hydroxide, or carbonate with hydrochloric acid: It also is used to prepare several other cobalt salts and in the manufacture of synthetic vitamin B12. Humidity indicator as a temperature indicator in grinding as a foam stabilizer in beer in invisible ink for painting on glass in electroplating and a catalyst in Grignard reactions, promoting coupling with an organic halide. But under unfavourable conditions, errors may amount to as much as ± 5% R.H., unless the corrections are used.Cobalt(II) chloride has several applications. teat papers can be estimated to about the nearest 1% R.H. The standards cover humidities above 50% R.H. Corrections are given for use when exposures other than 30 min. is sufficient except at very high humidities, where up to 2 hr. The influence of temperature and humidity on the time taken to reach colour equilibrium is described. Approximate corrections for temperature are given. Methods of impregnating the paper are described, also the above-mentioned method of preparing standards. A further improvement is the use of pure cotton tissue paper. Papers more suitable for use at high humidities have been prepared with cobalt thiocyanate solution. Alternatively, the addition of zinc chloride or certain other salts adapts the method for use at low humidities. The method can thus be adapted for accurate use at higher humidities. Certain salts, such as potassium thiocyanate and sodium thiosulphate, produce a similar, but much greater effect, and also produce stronger colours. Various colloid substrates other than paper, including mercerized cotton, cause the blue colour to persist at somewhat higher humidities possible uses of this are suggested. to the nearest 2% R.H., and above this range to the nearest 5%, except for low humidities at low temperatures. It is possible to measure humidities from 40 to 70% R.H. Colour standards for the matching of test papers are prepared by exposing papers over constant humidity solutions and then sealing them up in liquid paraffin between opal and clear glass. The time required for a piece of CoCl 2, paper to reach equilibrium with the atmosphere depends chiefly on humidity and temperature up to 2 hr. The paper is impregnated by dipping in a solution of CoCl 2.6H 2,O. It is shown that the colour is determined chiefly by the relative quantities of cobalt chloride and water in the paper. There is a close correspondence between colour and relative humidity, although the colour is influenced slightly by temperature. Cobalt chloride paper is blue at low and pale red at high humidities, with a series of lilac colours between. To meet the need for a simple method of measuring humidity in small spaces, a new method of using paper impregnated with cobaltous salts has been developed.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |