Sometimes I wonder about interesting things, such as how much energy would it take to boil all the water of Lake Washington:
- The volume of Lake Washington is 2.89 km31
- The average lake temperature is 9.71°C2
- It takes 4.19 Joules to raise the temperature of 1g of water by 1°C:
3
- The density of water is
Putting all that together, we get:
For comparison, the energy that hits Earth from the Sun in one second: 4
Basically, if we could focus all the energy from the sun that hits the earth, it would take… …to vaporize Lake Washington5.
This is a vast oversimplification of the forces and energies involved, but I think it’s still a pretty good estimate.
Update: Apparently I missed one critical element, enthalpy/heat of vaporization 6. “This energy breaks down the intermolecular attractive forces, and also must provide the energy necessary to expand the gas (the PΔV work). For an ideal gas , there is no longer any potential energy associated with intermolecular forces. So the internal energy is entirely in the molecular kinetic energy.”7
What we have above is the energy required to bring it up to 100°C, but not to vaporize it. To actually vaporize water that’s already at 100°C, we need to add an additional 8
Running this number back through our calculations, we now get:
This is still within one order of magnitude from my original answer and really only takes slightly longer for the sun to actually vaporize Lake Washington 9.
http://wldb.ilec.or.jp/Lake.asp?LakeID=NAM-09&RoutePrm=0:;14:load;14:load; ↩
Average of all temperature data for 2011 for the Lake Washington buoy: http://green.kingcounty.gov/lake-buoy/Data.aspx ↩
ROM estimate ↩
this is why I’m not a chemist ↩
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/phase2.html#c3 ↩
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/phase.html ↩
still a ROM estimate ↩
Let’s try it! We can build a giant solar oven
assuming you are only trying to heat the water to 100degrees C, and not actually boil it, this seems accurate. But, it is a vast underestimate if you are actually trying to vaporize the lake. As far as I can tell, you did not account for the phase change of liquid to gas. This, for liquid H2O to gaseous H2O, is remarkably energy intensive (apparently 2260 kJ per kg). Please see attached graphical representation for more… http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/phase.html
@Stefan Schmidt: You are correct, sir. I’ve updated the post with your findings. Interestingly enough, it only takes seven times as much time to actually vaporize it, which is still within one magnitude.
You say how to get it to100 but doesn’t it require additional energy to actually become a gas – http://en.wikipedia.org/wiki/Enthalpy_of_vaporization
let’s be honest andrew… you were trolling for the fellow nerds right? well you caught us. 🙂
@Stefan Schmidt: And yes..just trolling for nerds. Oh hey, look who I found! By the way, you may also find this recent Reddit interesting:
“IAMA physicist/author. Ask me to calculate anything” (http://www.reddit.com/r/IAmA/comments/uw3lk/iama_physicistauthor_ask_me_to_calculate_anything/)
Oh..I think this explains why when you boil water, the liquid water stays 100C. Once the water is 100C, the energy coming from the burner is used to maintain most of the water at 100C while vaporizing a small portion. Do I win science?
I would be in favor or heating it to 100C and then dumping in a few tons of jello mix. For science!
James Morton liked this on Facebook.
love the reddit post
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