Leather is considered a mixture rather than a pure substance due to its composite nature. When we talk about leather, we are referring to a material that is made from animal hides, often treated with various chemicals to enhance its properties. This process involves multiple components, including the collagen fibers from the hide and various tanning agents, dyes, and preservatives. Because leather comprises these different elements, it cannot be classified as a pure substance, which would be made up of only one type of molecule.
Additionally, the composition of leather can vary significantly depending on the animal source and the treatment processes used. This variability means that each piece of leather can have different characteristics, such as texture, color, and durability, further reinforcing the idea that leather is a mixture rather than a uniform substance. In conclusion, the presence of multiple components and the variability in its constitution are why leather is classified as a mixture.