👉 A proportion fluid refers to a liquid whose volume changes in response to temperature variations, maintaining a consistent ratio of mass to volume. This means that as the temperature rises, the fluid expands, increasing its volume while its mass remains constant, and conversely, as temperature drops, it contracts, reducing volume while retaining mass. This behavior is due to the fluid's molecular structure and intermolecular forces, which are sensitive to thermal energy. Unlike gases, which follow Boyle's Law more strictly, proportion fluids exhibit a more complex relationship between temperature and volume, often described by equations of state like the van der Waals equation. This property makes proportion fluids crucial in various applications, including heat transfer systems and chemical processes where precise control of fluid volume is necessary.