Everything there is to know about the Density of Water.

Water density is probably one of the most important contributing factors to life on Earth. Without the way the density of water changes with temperature, our humble planet would just be a sterile rock orbiting a small insignificant star. Do we take it for granted? Of course! How can you wonder at something which is free and comes out of a tap?

So what makes water, or specifically water density so special?
The simple answer is that the unique properties of water density make it stand out from the crowd.

At the molecular level, water is born from fire. Like a phoenix rising from the flames, the explosive combination of hydrogen and oxygen creates the very thing that is so stable and harmless and vital to our very existence, water.

This in itself is amazing but what makes water so special is the way it behaves on earth within the tiny sliver of temperature ranges which on a cosmic scale would be so insignificant as to be nearly irrelevant.
It covers about 72% of the Earth’s surface, and is around us everywhere; even in places where one assumes there is no water (its even found in the polar craters on the moon!), indeed we, just as about every other living organism are made up of up to 90% water.

Water can alternate between three states of matter, its most common form is its liquid state, maintained a normal atmospheric pressure between the temperatures of 0 degrees Celsius and 100 degrees Celsius.
When temperature rises or falls the density of water also starts to change. A solid at 0 degrees Celsius and under, while gaseous at a temperature of 100 degrees and over.

In other words, if we understand pure water at room temperature as being in one state and the mass are 1 g/cm3, then as the water changes states to either ice or steam its mass will change.
In some ways the actual density of water is something that is always in a state of flux and therefore we can conclude that water never has an absolute density, because water density will always vary with temperature.

Two rules dictate the specific density of water at any given moment, temperature and atmospheric pressure.
Without getting overly technical, density is defined as mass per unit of volume.

The commonly used formula to determine the density of an object is P=m/V

P= represents density (this is measured in Kilograms per cubic meter.

m= represents the objects total mass (this is measured in Kilograms)

V= represents the objects total volume (measured in cubic meters)

As mentioned earlier, the density of water varies with temperature, but has its maximum density of 1 g/cm3 (1 gram per cubic centimeter) at 4 degrees Celsius which is the foundation of the metric standard of length and weight.

When the temperature drops below 4 degrees Celsius, the density will become less than 1 g/cm3.

Water has a maximum density but only when it is liquid form, pure water. Other factors which can affect its density are the presence of impurities, such as is the case with tap water, or salt water which can contain minerals or salts.

The density of water will change upon heating, and as the temperature rises, the density will decrease. The solid state of most substances is usually denser than the liquid state, and in most cases sink when in solid form. This however is not true with water, which becomes less dense when in its solid state.

A block of ice or an ice cube when put in a liquid will float, just as an iceberg does. This is really important. Just think about that for a second. If the density of water increased linearly with temperature then the oceans would freeze all the way through, from the bottom up.