Water Behavior: Why Does Water Shrink When Heated?

Why does water shrink when heated below a certain temperature?

What is the specific behavior of water molecules that causes this phenomenon?

Answer:

Water shrinks when heated below +4 °C (40°F) because its density increases with decreasing temperature.

Water behavior: Water, like most substances, generally expands as it is heated. However, there is a specific temperature at which water behaves differently: below +4 °C (40°F). Below this temperature, water does shrink (or contract) when heated. This phenomenon is due to the unique behavior of water molecules.

At temperatures below +4 °C, water molecules start forming a crystalline structure, creating a stable lattice known as ice. When ice is heated, it absorbs thermal energy, causing the water molecules to vibrate and move within the structure, leading to an increase in volume.

However, above +4 °C, water follows the general rule of expanding when heated due to increased molecular motion. This anomaly below +4 °C is one of the reasons why ice floats on water, as it is less dense.