![]() ![]() Only under professional supervision. Warning! Substances of this experiment are toxic and highly dangerous for your health. The cobalt solution is carcinogenic - in the case of contact with skin, wash it away with water. When carrying out the experiment, wear gloves and protective glasses. This is because the chlorine ions force the water out of the water complex of cobalt. Adding concentrated hydrochloric acid to the solution changes the color of the solution to bluish-purple. Cobalt ions are hydrated in the solution and have a pink color. The cobalt chloride changes color because the salt in the solution dissociates into ions. If you add water to the bluish-purple solution, it will become pink again, while if you add concentrated hydrochloric acid to the second solution, it will become bluish-purple. Pour distilled water into one glass, and concentrated hydrochloric acid into the second – the color of the solution will change to bluish-purple. Pour the obtained solution into two glasses. But under unfavourable conditions, errors may amount to as much as ± 5% R.H., unless the corrections are used.Dissolve 10 g of cobalt chloride (II) in 100 ml of water. A paper slip may be lordotic in three to five chlorides and dried. teat papers can be estimated to about the nearest 1% R.H. Dry Cobalt chloride is blue, whereas damp ones pink. Cobalt chloride is an inorganic salt that is bright blue when it is not exposed to humidity. When testing for humidity, the experimenter can simply use cobalt chloride paper to detect airborne water particles. The filter paper can be cut into small strips and stored in a desiccator with dry silica gel. Soak filter paper in this solution, drain and dry in an oven (set at no more that 100 C), so that it is a definite blue colour. The standards cover humidities above 50% R.H. If water is present, cobalt chloride will change colors from blue to purple to pink. Dissolve 5 g of hydrated cobalt (II) chloride in 100 cm 3 of water (solution is TOXIC). 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. General Chemistry (with CD-ROM and InfoTrac) (7th Edition) Edit edition Solutions for Chapter 17 Problem 59E: A weather indicator can be made with a hydrate of cobalt(II) chloride, which changes color as a result of the following reaction.Does a pink color indicate moist or dry air Explain. 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. Such striking changes in color make cobalt chloride useful as a humidity indicator in weather instruments. It is possible to measure humidities from 40 to 70% R.H. As humidity increases, cobalt chloride changes color from sky blue to purple to pink. 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 doll's dress was impregnated with cobalt chloride and changed color from blue to pink when. The paper is impregnated by dipping in a solution of CoCl 2.6H 2,O. These chemical toys began to be sold as weather indicators. ![]() 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. ![]()
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