Note: On heating, the hydrates lose its water molecules and thus cobalt chloride turns to blue which is water free form. described as a hygrometr or humidity indicator which will change in color depending upon. Therefore, the water turns the blue cobalt chloride paper into the pink. For a novelty picture that urill to' you about the weather. New equilibrium with cobalt Po aged 2 to the 4th, the L two And to H 20. Note: You can also make a weather indicator by using a strip of blotting paper and soaking it in the solution of cobalt chloride in a similar way as described above. Such distinct change in colour makes cobalt chloride useful as the humidity indicator in weather instruments. tf the colour of the flower becomes pink on some day, it indicates a storm if the colour becomes bluish-pink, it indicates rain and if the colour becomes light blue, it indicates dry weather. Now, your weather-indicating flower is ready for use.Dip the blotting paper flower in this solution, then put the flower in a warm place to dry.Now take about 20 gm of cobalt chloride from a chemicals supplier or from your laboratory and make a strong solution of it in water.With the help of cotton thread and a sewing needle, tie it with the thin wooden stick.Take a small sheet of blotting paper and cut it in the shape of a flower, as shown in figure.Color reactions for spot tests on drugs are a relatively easy. A glass vial at right has a solu- tion of camphor and alco-. A spot test is a chemical reaction that occurs when a particular substance is added to an unknown. Continue using gloves when handling the paper until it is completely dry. Allow the dipped paper to dry by hanging it or laying it flat. Dip the cutout into the solution of 10 cobalt chloride. The solution should be 10 cobalt chloride crystals and 90 water. One thin wooden stick about 3 mm thick and 15 cm long Peculiar Instruments Intended to Show Weather Changes. Pour a small amount of cobalt chloride solution into the shallow pan.This project is based on the color change produced in cobalt chloride by the moisture in air.ĬOBALT CHLORIDE SHOULD BE HANDLED WITH SURGICAL GLOVES AND IN AN OPEN SPACE.ĭO NOT SWALLOW OR ALLOW IT TO GET INTO YOUR MOUTH. When the humidity is high, rain is likely, while a low humidity usually indicates a dry spell. humidity, can be used as the basis for forecasting the weather. Place 5 mL of the respective sample solutions into test tubes.The amount of moisture in the air, i.e. Measurement of the Color-Change Temperature. Because the color tone of the reference solution changes depending on temperature, a fine adjustment of the color by adding several drops of 6 M HCl may be required when the ambient temperature is lower than 20 ✬. In addition, a reference color solution of 0 = 0.1 M and 0 = 5.4 M, which is light violet, is prepared in the same manner. All the sample solutions prepared are pink-colored indicating a slight gradient in color tone, Figure 2(a). Table 1 lists the conditions for preparing the series of sample solutions using 0.1 M CoCl 2 and 6 M HCl, where the mixed solutions of the required volumes are diluted to 100 mL with water in a volumetric flask. previously clipped in the following solution : chloride of cobalt. After repeated trial and error to observe the color change clearly at a temperature ranging from 30 to 60 ✬, conditions for the hydrochloric acid solutions of 0 = 0.1 M and 0 = 4.5~5.2 M were selected. Homemade Humidity Indicator A simple weather indicator that may be used in. ![]() A series of aqueous solutions of CoCl 2 -HCl with varying 0 and a constant 0 are required. Figure 2 illustrates typical experimental steps. It is a skin, eye, and respiratory irritant and repeated exposure can lead to poisoning. #) is harmful by inhalation and ingestion. The present experiment is useful to deepen student understanding of the temperature effect on the equilibrium shift and to introduce chemical thermodynamics at equilibrium. Using the measured data for color- change temperatures and the calculated equilibrium constants at those temperatures, the standard enthalpy change DHº is evaluated by a van’t Hoff plot. Through a simple experiment of measuring the color change temperatures for a series of cobalt(II) chloride solutions with different concentrations of hydrochloric acid, the temperature dependence of the equilibrium constant is estimated. It was found that the equilibrium constant at the temperature of the color change between the pink octahedral complex and deep-blue tetrahedral complex can be expressed approximately as a function of the concentration of hydrochloric acid. For the equilibrium system of cobalt(II) chloride in hydrochloric acid, a simple student experiment to discuss quantitatively the equilibrium shift depending on temperature was examined.
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