Sensing ammonia using dry waters containing cupric chloride solution

Dry waters with cupric chloride solution–silica particles core–shell structures were prepared by a mixing method and were used as a detector for ammonia gas. The microscopy results showed that the dry waters were spherical and had an average diameter of 260 μm. When the dry waters was exposed to ammonia gas, their color were changed from green-blue to deep blue due to the generation of tetraamminediauacopper(II) complex ions. With the decrease of the diameter of the dry waters or the decrease of the concentration of cupric chloride solution, the dry waters became more sensitive to ammonia gas.