What do the formation of rust and cottage cheese have in common?

While they seem very different, the formation of rust and cottage cheese share a common process: chemical reactions involving the breakdown of larger molecules into smaller ones.

* Rust formation is a chemical reaction called oxidation. Iron (Fe) reacts with oxygen (O2) and water (H2O) to form iron oxide (Fe2O3), which we know as rust. This is a decomposition reaction, where the iron atoms are broken down and recombined with oxygen and water molecules.

* Cottage cheese formation involves the separation of milk proteins. The process starts with the addition of acid (like lemon juice) or bacteria (in the case of cultured cottage cheese) to the milk. This acidification causes the milk proteins (mainly casein) to denature and coagulate, separating from the whey (the watery part of the milk). This is another type of decomposition reaction, where the large protein molecules are broken down into smaller curd particles.

In both cases, the chemical reactions involve the breaking down of larger molecules into smaller ones, resulting in a change in the physical properties of the substance.