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I know Dr. Lavelle went into quite a bit of depth as to why steam causes burns worse than boiling water, but I am still a bit confused. Why does this occur? In my notes, I wrote that steam has a large enthalpy of condensation: is that the reason why?
I also believe that, through the diagram that he showed in lecture, steam is hotter than liquid because the temperature was much higher above 100 degrees, meanwhile the liquid for temperature went between 0 degrees and 100 degrees.
When steam comes into contact with skin, it encounters a phase change to a liquid and immediately releases many more kJ of energy as opposed to just boiling water which does not have to go through a phase change and therefore releases less kJ of energy.
Steam burns more because if you look at the diagram he showed us in lecture , it releases a lot more energy to go back down to its liquid phase. The release in energy is much more than if you touched boiling hot water.
Steam is worse than water even at the same temperature when coming into contact with your skin. This is because the steam has much higher enthalpy than the water, even if they are at the same temperature. Once the steam comes into contact with your skin, it condenses and this phase change releases much more energy than the hot water which only stays a liquid.
The steam has much higher enthalpy than the liquid, because more heat is required to achieve a gaseous state. Therefore, when it comes into contact with your skin and quickly condenses, it releases a large amount of heat in comparison to that that would be released by the liquid state.
Megan Kirschner wrote:Would anyone be able to describe the diagram you all are referencing? I was sick and unfortunately missed that lecture :/
The diagram looks like this:
Showing the actual diagram, which is the heating curve of water, you can see that it takes a lot more energy to transition from liquid to vapor than it does from solid to liquid. Therefore, steam carries much more heat for worse burns than boiling water.
Chantel_2I wrote:Is there a reason why the horizontal line for vaporizing water is so much longer than the one for melting ice?
It takes longer to vaporize water because there is a larger enthalpy, which means more heat has to be applied at a constant rate.
Steam has more energy than water, so the difference between the energy in steam and the energy of your skin is greater, and as such, when it comes into contact with you, it will transfer a correspondingly greater amount, leading to a more severe burn.
Steam has way more energy than liquid as a result of the energy required to vaporize liquid, and as a result, the phase change releases more energy onto your skin in the form of heat and burns more
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