Question

The soldiers of Napolean army while at Alps during freezing winter suffered a serious problem as regards to the tin buttons of their uniforms. White metallic tin buttons got converted to grey powder. This transformation is related to

• A. a change in the crystalline structure of tin
• B. an interaction with nitrogen of the air at very low temperature
• C. a change in the partial pressure of oxygen in the air
• D. an interaction with water vapour contained in the humid air

Answer 1

Answer: (A)

Tin exists in three solid forms, grey tin, white tin and rhombic tin and all these three forms are inter convertible as $\text{Grey}\text{White}\text{Rhombic}$ White tin is most stable form. The conversion of white tin in to grey tin takes place very slowly at 18°C. However, the temperature is low -50°C and a small amount of grey. tin is also present. The conversion becomes very rapid. This conversion is known as tin disease or tin post.