Cadmium sulfide

Cadmium sulfide is a chemical compound. Its chemical formula is CdS. It has cadmium and sulfide ions in it.

Properties
Cadmium sulfide is a yellow orange solid. It does not dissolve in water. It reacts with hydrochloric acid to make hydrogen sulfide and cadmium chloride. It is used in an odd reaction where cadmium sulfide is sprinkled into a sulfide solution and light is shined on it. It starts making small amounts of hydrogen gas. 

Occurrence
Cadmium sulfide is only found in two rare minerals. It is normally made artificially.

Preparation
Cadmium sulfide is made several different ways. Cadmium salts, normally the sulfate or the chloride (cadmium chloride), are reacted with hydrogen sulfide to make a bright yellow cadmium sulfide solid. When it is made for pigment, the cadmium sulfide is then washed, heated (to change it into the right form), and ground to a powder. It is then mixed with paint.

Uses
Cadmium sulfide is used as a yellow pigment. Cadmium yellow is the name of the pigment. If selenide is added during the roasting process (seen above in "preparation" section), it can make an orange or a yellow pigment. Cadmium sulfide is a good pigment because it does not break down easily, is very bright, and does not react with air like other pigments can. It is toxic, though. 

It is also used in photoresistors that are sensitive to infrared and red light. Cadmium sulfide is found around some bacteria that reduce sulfate to sulfide.

Related pages
Cadmium telluride, semiconductor
Mercury sulfide, bright red pigment, too toxic to be used
Zinc sulfide, phosphor

Category:Cadmium compounds
Category:Sulfides