cobalt chloride forms pink crystals. when they are heated water is evolved an they turn blue. can you please explain how you could ue cobalt chloride as a test of water.
I would put the crystals in a porous vessel, with a see through window. Blue means wet.
Doesn't blue mean dry; pink means wet?
Yes, cobalt chloride can be used as a test for the presence of water. When anhydrous (dry) cobalt chloride is exposed to water vapor or even moisture in the air, it readily absorbs water and undergoes a chemical reaction known as hydration.
Here's how you can use cobalt chloride to test for water:
1. Preparation: Start with a small amount of anhydrous cobalt chloride crystals. These crystals are typically blue in color.
2. Observation: Place the anhydrous cobalt chloride crystals in a dry container or test tube. Initially, the crystals should appear blue.
3. Exposure to Water: Expose the cobalt chloride crystals to a source of water, such as by placing the container in a damp environment or directing water vapor towards the crystals. Alternatively, you can drop a small amount of water directly onto the crystals.
4. Observation of Color Change: As the cobalt chloride absorbs water, it undergoes hydration and its color changes. Initially, the blue crystals start turning pink. This change in color is due to the formation of hydrated cobalt chloride, which is pink in color.
5. Evaporation: If you want to observe the reversibility of the reaction, you can heat the hydrated pink cobalt chloride crystals. As they are heated, water molecules are released, and the compound dehydrates, returning to its original blue color.
In summary, if cobalt chloride turns from blue to pink upon exposure to water, it indicates the presence of water. This reaction can be used as a simple test to detect the presence of moisture or water vapor.