Final answer:
Tin pest, or tin disease, is the conversion of malleable white tin (ß-tin) to brittle gray tin (α-tin) at temperatures below 13.2°C, leading to disintegration of tin objects. It is a structural transformation, not a corrosion process and was historically noted during Napoleon's Russian campaign.
Step-by-step explanation:
Tin pest, also known as tin disease, is the transformation of tin from a metallic form to a brittle, non-metallic form at low temperatures.
Specifically, tin has two allotropes: white tin (ß-tin) and gray tin (α-tin). White tin is the stable metallic form at temperatures above 13.2°C and it is malleable.
Below 13.2°C, white tin slowly converts to gray tin, which is brittle and powdery. This conversion, which is exothermic, can lead to the disintegration of tin objects in cold weather as the less dense gray phase progresses from the spot of origin.
This phenomenon has historical significance, as it is said to have affected Napoleon's army during the invasion of Russia in 1812, when the tin buttons of the soldiers' uniforms disintegrated in the cold, impacting their ability to stay warm.
Tin pest is not a result of a reaction with water, sulfur compounds, or acids, but a change in crystal structure due to temperature.
Corrosion, on the other hand, typically involves a naturally occurring electrochemical process where metals are degraded, which is not the case with tin pest.