Increased pressure causes water molecules to pack closer together, resulting in a higher density. Conversely, decreased pressure leads to greater intermolecular spacing and lower density.
Understanding the Relationship
The density of water, like most substances, is directly affected by pressure. This means that as pressure increases, the density of water increases, and as pressure decreases, the density decreases. This is because pressure forces the water molecules closer together, reducing the volume occupied by a given mass of water and thus increasing its density. While water is often considered incompressible, it does exhibit a small degree of compressibility, particularly under very high pressures. At normal pressures, the change in density is negligible, as noted in various sources. [Source: Physics Stack Exchange, "Hydrostatic pressure - doesn't density vary with depth..."]
Several sources confirm this relationship: [Source: Engineering.com, "How does pressure affect density of fluid?"] indicates an inverse relationship (density decreases as pressure increases), but this is likely an error. The vast majority of sources confirm the direct relationship.
Examples and Practical Insights:
- Deep ocean: At great depths in the ocean, the immense pressure causes a slight increase in the density of water.
- High-pressure experiments: Scientific experiments often involve applying high pressures to liquids to observe changes in their properties, including density.
Note: The effect of temperature on water density is also significant. The density of water reaches a maximum at 4°C (39°F) at standard pressure, and it decreases at both higher and lower temperatures. [Source: LSBU Water, "Water density"]
While the effect of pressure on water density is measurable, it is generally small compared to the effect of temperature at common pressures. [Source: Engineering Toolbox, "Liquids - Densities vs. Pressure and Temperature Change"] Numerous sources ([Source: Byjus, "What Is The Relation Between Pressure And Density?"]; [Source: Quora, "How does pressure affect density?"]; [Source: Vedantu, "Density of Water – Effect of Pressure and Temperature"]) reiterate this direct relationship between pressure and density.
