What is hotter, the boiling water or the steam?

RickJ

I think at the surface they would be the same, but as the steam rises it, of course, cools.

rudi_in

First of all, thank you for posting your question to the Ask Me Help Desk! This can be a somewhat tricky concept so let me begin with a little background information with which you may already be familiar.



The boiling point of water is 100 degrees Celsius. At this temperature the water will begin to change from the liquid state to the gas state. In order for this change to take place, additional energy is required. In fact, every gram of liquid water requires 540 calories of heat energy just to convert it to steam. This is called the Heat of Vaporization. During the conversion process, temperature does not increase. It is, therefore, possible to have both liquid water and steam that exist at 100 degrees Celsius. While they both would exist at the same temperature, the steam would have a lot more heat energy due to the additional 540 calories per gram of heat energy that has been absorbed.

This is why steam burns are worse than the water burns.

The temperature of steam can continue to rise well above 100 degrees Celsius if it is contained and additional heat energy continues to be added but the water in liquid form will not go above 100 degrees as long as it does not have any impurities in it and assuming that standard pressure remains constant.

I hope that this information was useful to you.

jadedhills

Water only boils at 100 degrees At Sea Level steam is water with more energy in it so it is hotter than boiling water, (superheated water) also steam is far more likely to scald dangerously, it is as steam condenses that it releases energy. and starts to cool and condence

rudi_in

It is important that we are careful with our use of words like "hotter" or "colder". These are words of comparison relative to another substance, not words of measurement. Steam has more heat energy than liquid water but not necessarily a higher temperature.

caibuadday

it take about 142 btu to bring 1 pound of water to 212F, but it take about 970 btu to turn 1 pound of water into 212f steam..........

makdan

Regarding augustknight's comment: Actually, water, steam, and ice can all co-exist at a single temperature -- the so-called triple-point, but I don't remember what temperature and pressure this occurs at.

Capuchin

the triple point of water is at 273.16K and 0.006 atm.