Steam and burns

[Carina H - 2G]

Hi!

Could someone explain why steam causes burns? I somewhat understand it but want to clarify that it is because the temperature and energy required to make vapor is highest. Thanks!

[Chem_Mod]

When you look at the heating curve, it can be seen that the Hfusion is very small compared to the Hvaporization. This means that when vapor condenses into liquid, such as when it touches your skin, a very large amount of energy is released which causes the burn. This is indicated by a very long, flat line if you're looking at a diagram.

[Grant_2A]

Essentially vapor causes really bad burns because when looking at the heating curve for water, it requires the most amount of energy to get water to to turn into a vapor, so therefore it also releases the most energy as heat. That was my understanding at least, hope this helps!

[Jordyn Lee 1J]

Hi, looking at the heating curve for water, steam causes more severe burns because the heat supplied to go from a liquid to vapor is very large (40.7 kJ.mol^-1). This means that when vapor touches skin, it will release a lot more heat than liquid water at the same temperature.

[Jessica Cornelia Hongarta 1G]

Hi! Yes, you are right. So, for steam, since the H vaporization is high, there is an addition of 40.7 kJ/mol as steam condenses to liquid (when steam cools down as it comes in contact with a colder surface) before it cools down to a lower temperature (+5 kJ/mol). Thus, steam will release a really huge amount of energy (about 46 kJ/mol) compared to boiling water that is already in liquid form (only 5 kJ/mol). Which is why steam cause more severe burns.

[Audrey Banzali-Marks 1A]

When we put a substance through a phase change, it doesn't change temperature because all of the added energy is going towards changing phases. Consequently, steam would cause more severe burns because not only does it contain the enthalpy required to heat water to 100 degrees Celsius, but it also contains all the enthalpy required to convert that 100 degree C liquid water to water vapor.

[joshua_quinn_1C]

Hi! Steam causes more burning than water at the same temperature because if you look at the heating curve of water, the water vapor contains more energy and heat that was put into it during the process of vaporization. This is indicated by the long straight line between liquid and vapor. As a result, the larger amount of energy and heat within steam, although at the same temperature, will cause worse burns. Hope this helps!

[Kaitlyn Bateman 1L]

Hi! Because the temperature of the steam is high, it can still cause burns. However, the burns caused by steam are much worse than burns caused by liquid water. This is because the deltaH of the vapor is much higher than the deltaH of the liquid and the transfer of that energy to your skin has a greater effect. Additionally, even after the vapor condenses onto the skin, it still must cool until the skin is no longer burning. Hope this helps!

[Reagan Feldman 1D]

In addition to the other posts, if you look at the heating curve for water, you can refer to the area under the curve. Looking at the graph from left to right, heat is released. The area from the point at which water is 100 degrees C in liquid form to where it releases heat back to its "endpoint temperature" is fairly small. The point at which water is 100 degrees C back to that same endpoint temperature in vapor/steam form, however is much larger. This is because the steam must first condense on the skin, releasing much more heat than the boiling water, and therefore causing a more severe burn.

[elliemehrara]

If we consider the heating curve for water, we can see that the heat of vaporization is very high compared to the heat of fusion. This means that changing water from liquid into vapor requires a lot of energy. When the steam hits your arm, it will condense because your arm is cooler. This condensation will transfer energy to your arm, burning it worse than water does.

[Kathleen Wijaya 3L]

The enthalpy for vaporization is very high and releases more heat energy than boiling water at the same temperature.

[Mara Crooks 1F]

The way interpreted it was that vapor releases more energy as heat than liquid. This makes it seem hotter and would burn more severely than liquid. There is another post similar to this with a few more thorough responses called "Enthalpy" from January 19, 2022.