what is the main purpose of a drying agent
Desiccant
Sometimes a humidity indicator is included in the desiccant to show , by color changes , the degree of water - saturation of the desiccant . One commonly used indicator is cobalt chloride ( CoCl ) . Anhydrous cobalt chloride is blue . When it bonds with two water molecules , ( CoCl 2H O ) , it turns purple . Further hydration results in the pink hexaaquacobalt ( II ) chloride complex ( Co ( H O ) ) Cl .
Sometimes a humidity indicator is included in the desiccant to show , by color changes , the degree of water - saturation of the desiccant . One commonly used indicator is cobalt chloride ( CoCl ) . Anhydrous cobalt chloride is blue . When it bonds with two water molecules , ( CoCl 2H O ) , it turns purple . Further hydration results in the pink hexaaquacobalt ( II ) chloride complex ( Co ( H O ) ) Cl .