The compound Na2S or Sodium sulfide is soluble in
water. This compound is a water-soluble salt that give strong alkaline
solutions. When exposed to air or humidity this compound gives-off hydrogen sulfide
that smells almost the same as rotten eggs.
This chemical is commonly used in the pulp and
paper industry. Sodium sulfide compounds are usually used in chemical
photography, textile bleaching, making dyes, and even detergents.
The other 3 compounds are non-soluble in water. Their
compositions are mostly metal in nature and require other process to transform
them into different compound forms.
