Why does steam cause more severe burns than boiling water?

[Stella Huang 2C]

Hi! I know we went over this question during lecture, but I'm still a little confused. I remember Dr. Lavelle provided the example of two patients who both were burned by 18g of 100 deg C water, and I had this in my notes:

- Assuming the skin temperature was 25 deg C, the patient burned by liquid water had to increase by 75%, or 7.5 kJ
- Vapor still needs another 5 kJ when it cools down, because of the large enthalpy of sublimation
(However, looking back I don't remember the exact line of reasoning as to why I put these down)

Here's the slide for the question:

Could someone help clarify my understanding or explain what helped you understand?

Thank you so much!

[Timothy Liu 3C]

You can see that when going from liquid to vapor, water requires large amounts of heat before it actually transitions to the vapor phase compared to only heating up water. When your skin comes in contact with steam, that very large amount of heat that is stored gets released onto your skin. The energy released by steam has in addition, the heat of vaporization.

[705735243]

When steam comes in contact with skin, the steam suddenly releases about 40 kJ of heat to condense. Then it continues to cool and releases even more heat.

[Raya Amin 2A]

To add on to what everyone else is saying, you can see from the graph that the enthalpy of vaporization is much larger compared to the enthalpy of fusion and the enthalpy change in heating up the water. This heat is stored in the water as it is being vaporized. As a result, when the steam comes into contact with a cooler surface (the skin), it condenses, releasing all of this stored heat. Boiling water doesn't contain the same amount of stored heat, and therefore doesn't cause as severe burns.

[Jasmine Patel 1B]

To put it simply... since more heat was put in to get steam initially, more heat will be transferred to the skin when cooled.

[Julia Scheithauer 1J]

A lot of heat energy was put into the water in order to get it into the steam phase, so when steam comes into contact with your skin it cools down rapidly and condenses into water, releasing all of that stored energy as heat onto your skin.

[eriko vong 3D]

More heat is required for water to turn into steam compared to the heat required for water to boil, therefore, more heat is released when steam comes into contact with the skin.

[Stella Huang 2C]

Thank you all so much this clarifies a lot! :)

[305943084]

A huge amount of heat is required to transfer liquid water into its gas state(as referred by the graph) and upon touching steam all those heat are released onto your skin.
That's bond to hurt a lot lol.

[suhas yarra 2D]

Because steam is gaseous water, which has more energy added to it to come to that state from boiling water. Therefore, more energy will hit your skin and cause more severe burns in the case of steam.

[Rachel Lee]

Looking at the graph we can see that it takes significantly more heat to turn liquid water into vapor/steam in comparison to how much it takes to boil water. Thus, when steam touches skin it will release that much more heat onto it compared to boiling water and cause more severe burns.

[Rubani Chugh 2K]

When someone is burned by boiling water (at 100 degrees C), 5 kJ of heat is released onto their hand. On the other hand, steam would release 40.7 kJ of heat, which is a significantly higher amount of heat. This is because when vapor comes in contact with something cooler, such as one's hand, it condenses very quickly (vapor to liquid phase change). The amount of heat released during this phase change is called the enthalpy of condensation (40.7 kJ) and this what causes steam to burn so severely.

[noahgraham]

The steam can hold more energy at 100 degrees than the water can because of the difference in phases and their capacities so when these two substances come into contact with the skin both at 100 degrees, more energy (heat) is being transferred from the steam to your skin than there is from the water to the skin which is why it burns more. The phase changes again when the water in both forms comes into contact with the skin so changing from the vapor phase into the liquid phase takes more energy (heat) than liquid back to a cooler liquid.

[Stella Huang 2C]

When someone is burned by boiling water (at 100 degrees C), 5 kJ of heat is released onto their hand. On the other hand, steam would release 40.7 kJ of heat, which is a significantly higher amount of heat. This is because when vapor comes in contact with something cooler, such as one's hand, it condenses very quickly (vapor to liquid phase change). The amount of heat released during this phase change is called the enthalpy of condensation (40.7 kJ) and this what causes steam to burn so severely.

Thanks Rubani the number comparison helps a lot in my understanding!

[Louie_Reichmuth_2K]

Since, as can be seen by the graph, there is a large amount of heat that is put into vaporizing liquid water into its gaseous state, when the vapor actually hits your skin it has all of this heat and energy in it. This is what causes heat to feel so hot when it touches you.

[Arielle Luong]

when looking at the diagram, you can see that you need to add a lot more energy/heat for water to become vapor. This heat is what causes the severeness of the burns to increase because that eenrgy is being transferred to your skin.

[VictoriaPietrusiew2H]

Since more heat is required to turn water into steam than the heat required for water to boil, more heat will be absorbed into the skin when coming into contact with it.

[mieke van daelen 2I]

There is more heat required to create steam so therefore this is more heat transferred to whatever comes in contact with the steam, leading to a more severe burn then boiling water.

[mieke van daelen 2I]

There is more heat required to create steam so therefore this is more heat transferred to whatever comes in contact with the steam, leading to a more severe burn then boiling water.

[Abby Freeman 1C]

Steam has the heat energy to get to boiling water and the heat of vaporization whereas boiling water only has the heat energy to be boiling water.

[Abby Freeman 1C]

Steam has the heat energy to get to boiling water and the heat of vaporization whereas boiling water only has the heat energy to be boiling water.

[Rebecca_Park_1G]

Steam causes more severe burns than boiling water because per the heating curve, steam is attained with greater heat. As such, this greater amount of heat will transfer to the skin, which results in burns of much greater severity.

[Sean_Hertel_3A]

Hi! Steam causes more severe burns than water because not only does it have the energy from its temperature, it also has the energy used to vaporize it, whereas liquid water lacks the same energy as a gas. After water comes to a boil, as you can see from the diagram, it requires much more energy to be vaporized. This difference is what causes more severe burns when it's in its gaseous state.

[Tiffany Ngan 1K]

Steam causes more severe burns than boiling water because the amount of heat required for a phase change from liquid to vapor is much higher than the energy required to change from solid to liquid. Therefore, when your skin comes in contact with steam, that amount of heat that is stored in order to achieve its vapor state gets released onto your skin.

[Tiffany Ngan 1K]

Steam causes more severe burns than boiling water because the amount of heat required for a phase change from liquid to vapor is much higher than the energy required to change from solid to liquid. Therefore, when your skin comes in contact with steam, that amount of heat that is stored in order to achieve its vapor state gets released onto your skin.

[Roni Nissim 1D]

This reaction is exothermic, so along with it being hot it also releases extra heat from being exothermic.