Cocl2 is often used in hygrometers. search the internet to determine why? how does this relate to this experiment?

CoCl2 changes color depending on the amount of water present. When it is dry, CoCl2 is pink but as it absorbs the water in the air, it would turn back to blue. As hygrometers measure the amount of water in the air, the color change can be used as a simple hygrometer.