Anhydrous: Opaque crystalline powder.

Pentahydrate: Colorless and transparent monoclinic crystal.

Anhydrous:

1. For the manufacture of fixing powder and photography industry preparation fixing agent, desiccant. Used as a reducing agent of dichromate in tanning leather.
2. It can be used to synthesize insecticides on pesticides.
3. Used as pulp and cotton bleaching after chlorination agent, food industry used as chelating agent, antioxidant, pharmaceutical industry used as detergent, disinfectant.

Pentahydrate:

Used as fixing agent of photograph, electroplating, reducing agent, dechlorinating agent, fading agent, etc. Widely used in textile, printing, dyeing, leather, water treatment, paper making, mining, synthetic dye, medicine, insecticides, etc.