Final answer:
Materials can crack when exposed to sulfur compounds such as hydrogen sulfide and thiols, as these compounds can react with and break down their structure.
Step-by-step explanation:
Some materials crack when exposed to sulfur compounds like grease or oil due to chemical reactions that cause deterioration. The presence of sulfur compounds such as hydrogen sulfide (H₂S), which is known for its characteristic rotten egg smell, often leads to the degradation or cracking of certain materials, particularly polymers. This is because sulfur compounds can react with the polymer chains, leading to a breakdown of the material's structure.
Substances such as thiols or mercaptans, with sulfur functioning as an analog to oxygen in alcohols, can also participate in such reactions, leading to the mild oxidation of thiols into disulfides. This type of reaction shows the vulnerability of certain materials to sulfur-containing substances, emphasizing the need for caution when handling these chemicals.