Liquidphase

A liquid phase is one of the fundamental states of matter in which a substance has a definite volume but no fixed shape. Liquids flow readily and assume the shape of their container, spreading to fill the available space while maintaining near-constant density. The molecules in a liquid are less tightly bound than in a solid, allowing relative movement that gives fluids their characteristic deformability and ability to form interfaces with gases or other liquids.

Key properties of the liquid phase include density, viscosity, surface tension, and compressibility. Liquids are typically less compressible than gases and more compressible than many solids. Viscosity measures resistance to flow, while surface tension arises from cohesive forces at the liquid’s surface and governs phenomena such as droplet formation and capillary action. Miscibility describes whether different liquids mix to form a single phase or separate into distinct phases.

Liquids participate in phase transitions with other states of matter. Heating a liquid can produce a gas at the boiling point, while cooling can form a solid at the melting point. Phase diagrams depict conditions of pressure and temperature under which a substance exists as solid, liquid, or gas, and may include liquid-liquid immiscibility, critical points, and triple points where three phases coexist.

Common liquids include water, organic solvents, and various molten metals. Liquids are central to chemistry, engineering, biology, and environmental science due to their transport properties, chemical reactivity in solution, and role in separation and purification processes.