It’s a common misconception that steam is visible. The characteristic white mist that we see rising from a boiling kettle or the cooling tower of a power station is, in fact, haphazard clouds of water droplets forming through the condensation of steam in the cooler air.
Indeed, if steam was simply a mist of water droplets and nothing more, it wouldn’t be anywhere near as exciting as we’re about to reveal. No, true steam, generated when water molecules receive an energy excess great enough to break down their bonds, is of interest due to the massive growth in volume brought about by its phase change.
This expansion clocks in at 1,700 times the volume of its liquid state (water), a factor of 30,600:18.
As such, a single mole of water, a mole of a substance is the mass of the material in grams that is numerically equal to its molecular mass, is 18 grams. However, at standard temperature and pressure, that mole expands to fill a volume of 22.4 liters when vaporized.
Conversely, the same factor is attributable to the reversed state change (ie condensation). This process is far from merely a scientific curiosity. It is fundamental to understanding how arguably the biggest social, industrial and economic upheaval the world has ever witnessed came to bear over a period of 200 years.
That upheaval was the Industrial Revolution and that simple, invisible, beautiful expansion of volume was the driving factor of the steam engine, one of the most important inventions ever created and the machine that essentially built the modern world.