Question

Water is heated from ${{0}^{\circ }}C$ to $~{{10}^{\circ }}C$. How does the density of water change with temperature?
A. On heating, density of water increases.
B. On heating from ${{0}^{\circ }}C$, the density of water increases up to ${{4}^{\circ }}C$and then decreases beyond ${{4}^{\circ }}C$.
C. On heating, density of water decreases.
D. Density of water is independent of temperature.

Answer 1

Whenever density increases the volume decreases and whenever the volume increases the density of the material decreases. As the temperature of the substance increases the mean molecular distance is also increased.

Complete step by step answer:
When we heat water from ${{0}^{\circ }}C$, we know that on heating, the volume of water decreases as the density of water decreases. But we can see this effect of decreasing volume and increasing density, till ${{4}^{\circ }}C$, and the reason is because of the density of ice is maximum at ${{4}^{\circ }}C$. So after ${{4}^{\circ }}C$ the density of the water decreases and as a result the volume of the water increases.
The prime reason for this phenomenon is because the hydrogen bond in the ice gets cleaved due to the melting of ice.

Therefore the correct option is option B, which is on heating from ${{0}^{\circ }}C$, the density of water increases up to ${{4}^{\circ }}C$ and then decreases beyond ${{4}^{\circ }}C$.

Additional Information: Temperature can also affect the density of water. When a fixed amount of water is cooled or heated, its density changes. That is, when we heat water, the water expands, and its volume increases. And we know that the warmer the water, its volume increases, and the density decreases as the water tends to change itself from liquid to gaseous form.
Some other factors affecting density also include salinity.

Note: We should know that below ${{4}^{\circ }}C$ hydrogen bonding becomes more prominent and we also know that hydrogen bonds are generally longer than the typical distance between the water molecules at this temperature.