CoCl3.6H20 forms pink crystals. When they are heated water is evolved and they turn blue. Explain how you could use cobalt chloride as a test for water??
see whether they are pink, as opposed to blue.
google can provide many helpful discussions.
I found this on Google although it is about CoCl2.
https://chlorine.americanchemistry.com/Science-Center/Chlorine-Compound-of-the-Month-Library/Cobalt-Chloride-Colorful-Moisture-Detector/
To use cobalt chloride as a test for water, you can follow these steps:
1. Obtain cobalt chloride crystals: Start by obtaining cobalt chloride crystals, CoCl3.6H2O, which are usually pink in color.
2. Observe the original color of the crystals: Take a few crystals of cobalt chloride and observe their color. The pink color indicates the presence of water molecules within the crystal lattice.
3. Heat the crystals: Heat the cobalt chloride crystals either by placing them on a hot plate or using a Bunsen burner.
4. Watch for color change: As you heat the crystals, observe any changes in color. In the case of cobalt chloride, the crystals gradually lose their water molecules and turn blue. This color change occurs due to the formation of anhydrous cobalt chloride, CoCl3, which is blue.
5. Identifying the presence of water: By observing the change in color, you can determine the presence of water. If the cobalt chloride crystals turn from pink to blue upon heating, it indicates the release of water vapor. This is an indication that water was initially present in the cobalt chloride crystals.
Using cobalt chloride as a test for water is based on its property of being a hydrate and its distinct color change when heated. The test is particularly useful when detecting the presence of water in solid materials or as a qualitative demonstration in educational settings.
To use cobalt chloride as a test for water, you can follow a simple and straightforward procedure. The change in color observed when cobalt chloride is exposed to water is due to the chemical properties of the compound.
Here's how you can perform the test:
1. Obtain a small amount of cobalt chloride crystals, preferably in solid form.
2. Place the cobalt chloride crystals in a clean, dry container such as a test tube or a petri dish.
3. Observe the original color of the cobalt chloride crystals. In this case, the crystals are pink in color.
4. Carefully heat the container containing cobalt chloride crystals. The heat can be applied using a Bunsen burner or any other suitable heat source.
5. As you apply heat, closely monitor the container and observe any changes in color.
6. As the heat is progressively increased, you will notice the pink cobalt chloride crystals transition to a blue color.
7. At the point where the crystals turn blue, stop applying heat, and take note of the color change.
The science behind this color change lies in the fact that cobalt chloride forms a hydrated complex with water molecules. The original pink cobalt chloride crystals, CoCl3.6H2O, contain six water molecules per cobalt chloride unit.
When heated, the hydrate loses its water molecules through a process called dehydration. As the water molecules are expelled, the cobalt chloride undergoes a chemical change and forms a new compound, CoCl3. This anhydrous cobalt chloride takes on a blue color.
By observing this color change, you can infer the presence of water. When cobalt chloride is exposed to moisture or even high humidity, it can reversibly absorb water from the air and convert back to its pink hydrated form.
Therefore, if you expose cobalt chloride crystals to a sample suspected to contain water, a color change from pink to blue would indicate the presence of water. This property makes cobalt chloride a useful compound for simple water detection tests in various applications.