Severity of Burns

[605720459 1I]

Why does water vapor cause more sever burns than liquid when they are the same temperature? Dr. Lavelle describes that even when the vapor and liquids are at the same temperature, vapor causes more severe burns. On a similar note, how can they be the same temperature, 100 degrees Celcius is the phase change temperature?

[elliemehrara]

Water vapor causes more severe burns than liquid water because when the water vapor hits your skin and condenses, it releases the heat of vaporization in addition to the heat associated with the temperature change (100 degrees Celsius to skin temperature). On the other hand, when water at the same temperature hits your skin, it will only release the heat associated with the temperature change. This means that water vapor will release a lot more heat onto your skin than liquid water, therefore causing a more severe burn.

[amara ajon 1d]

Hi,
Water vapor releases more energy as it touches skin (since it needs to go from gas to liquid AND account for the temperature change), which causes a more severe burn than just boiling water touching skin.

[Alice Guey 1B]

The above replies did a good job explaining why water vapor causes more severe burns than liquid water. In regards to how water vapor and liquid water can be the same temperature, it is because during phase change, heat energy is being used to break the bonds between water molecules and not to raise the temperature of the water.

[Allison Li 2F]

Water vapor needs to first be converted to liquid, which takes more energy. If you look at a phase change diagram, the area under the curve is much greater for water vapor than it is for just liquid. This corresponds to the additional step water vapor needs to take that liquid water does not.

[jaycmartinezDisc3b]

Hi, the reason why steam/water vapor causes more severe burns than liquid is because of the additional energy that is being released when the steam condenses into a liquid. So not only are you dealing with the actual heat of the steam by itself, you are also dealing with the energy of the steam going to a liquid. Hope this helps :)

[Matthew Vu 3C]

Water vapor causes more severe burns than liquid because water vapor releases energy as it condenses, and then on top of that, you have the energy from the liquid..

[Aaron Kwan 3B]

As illustrated in Dr. Lavelle's lecture, steam holds around 5-6 times more heat energy than water at the same temperature. Because this energy is instantly given off in order to change steam to water, you receive many kJ of energy at once.

[Coraly De Leon]

IN short, steam burns more than water because it has more energy. This is because more energy is required to break the bonds that keep the water a liquid.

[Martha Avila 1I]

Hello. So from what I understood in class it takes more heat energy for water in its liquid form to phase change to water vapor. Once water has phase changed from a solid to a liquid it takes less heat energy to get this liquid water to start boiling. So the more heat energy needed is what causes water vapor to create a more severe burn. Hope this helps!