When water is heated from 0°C to 10°C, its volume

Water exhibits an anomalous density behaviour: when heated from 0 °C up to about 4 °C it contracts (volume decreases) and reaches its minimum volume (maximum density) near 4 °C; upon further heating above 4 °C it expands as normal. Therefore, heating water from 0 °C to 10 °C causes the volume to decrease first (0→4 °C) and then increase (4→10 °C). Microscopically, this arises from the hydrogen-bonded network in water—warming from 0 to 4 °C breaks some open, low-density structures causing closer packing, while further heating increases molecular kinetic motion and average separations, giving normal thermal expansion (internal concept).