Difference Between Steam and Vapor

Steam vs Vapor

We are all familiar with steam, don’t we? We boil water in a pan and see its vapors coming out when the water reaches its boiling point. It is nothing but water in gaseous state and returns to its original state (that is water) upon cooling. Upon heating water in a kettle, we see a cloud coming out of the nozzle after some time, which people incorrectly refer to as steam. If steam is vapor, we cannot see it just as we cannot see vapors of a gas. The vapors of water are nothing but water droplets that mix with air mass to produce a cloud. Giving heat to the nozzle with a gas torch makes this cloud disappear though water vapor is still coming out. So what are the differences between steam and vapor?

Vapor is any substance in a gaseous state. Thus steam is just an example of a vapor. In fact, steam is one of the most common examples of vapor. It forms when water is boiled but vaporization also takes place when we hang washed clothes in air. It is then called evaporation but the same vapor is called steam when we boil water.

So the difference between vapor and steam is purely one of temperature. Water vapor (as in evaporation) is at the same temperature as the air outside. But in case of steam, water is at boiling point or higher. If we talk in terms of chemical composition, there is no difference between vapor and steam.

Steam is nothing but water that escapes the surface of water in the form of gas when it is boiled. Steam exists only when water is above 100 degrees centigrade and is composed water molecules that behave like a gas. Steam is also called water vapor above boiling point.

In brief:

Difference Between Steam and Vapor

• Water vapor is water that is in gaseous state while steam is water that has been created by heating water beyond its boiling point

• Steam is invisible much like vapor and what one sees coming out of kettle is steam that has actually condensed and technically no longer steam.