I know water freezes at 0 degrees celsius and that water boils at 100 degrees celsius. I do not understand how to use the formula given: Q=mLv .
Can someone explain this for me?
I was thinking the answer would be turning water into steam because it takes more heat to boil water then it does to melt ice, right?
2007-01-17 07:00:29 · 7 answers · asked by whispertree 3 in Science & Mathematics ➔ Physics
steam
look up the
heat of vaporization (Lv really L subscript v)) and compare it with the heat of fusion (Lf really L subscript f).
the equation only helps get you one of the numbers you need to compare (the energy required to create steam).
Lv=40.65 kJ/mole vs Lf=6.039 kJ/mole for water under stp conditions
There's lots of equations and predictors for this stuff based on bond strengths and all that, but basically to really know you go look it up in a table.
2007-01-17 07:03:44 · answer #1 · answered by David E 4 · 1⤊ 3⤋
You need to find both the heat of fusion of water and the heat of vaporization of water. Each of those is the amount of energy required to do the respective phase transition at the freezing or boiling point. Which ever is larger will be the one that requires the most energy.
I don't understand the equation you've given, because I'm not familiar with those terms
The heat of fusion and the heat of vaporization will be given in units of joules/gram or something like that. If you multiply the mass of water by the heat of fusion or the heat of vaporization, you'll calculate the energy needed for that phase change.
2007-01-17 07:11:37 · answer #2 · answered by hcbiochem 7 · 1⤊ 0⤋
Q = released energy or required energy to reorganize molecules.
m = mass (500 gs)
Lv = latent heat of vaporization (2,253,795 joules/ kg of water)
Lf = latent heat of fusion (334,584 joules/ kg of water)
Lf definition = The amount of energy it takes to turn 1 Kg of 0 degree C. ice into 0 degree C. water.
Lv definition = The amount of energy it takes to turn 1 kg of 100 degree C. water into 100 degree gas (steam)
As you can see you were correct. It takes more energy to vaporize water (without a temp change) than to melt ice (without a temp change). You do the math. Just; divide Lf & Lv values above by (2) for 500 gs.
2007-01-17 08:39:06 · answer #3 · answered by HeyDude 3 · 0⤊ 0⤋
It's equal.
It takes 1 calorie to raise 1 g of water, 1 degree Celsius regardless of it's initial state (solid, liquid or vapor).
To get 500 g of ice from 0 degrees C to 1 degree C, it would be 500 calories.
To get 500 g of (already boiling) water at 100 degrees C to 101 degrees C (steam), it would need 500 calories.
2007-01-17 07:07:20 · answer #4 · answered by Gary D 7 · 1⤊ 3⤋
Melting 500 G of 0 C ice. I think this is right because you will need energy to break the solid bonds while with the liquid, the bonds between the water molecules are somewhat weak any way. Solid bonds are generally stronger than liquid bonds
2007-01-17 07:05:15 · answer #5 · answered by lexi84 1 · 0⤊ 3⤋
turning 500g of 100c water inti stream because there are 3 kinds of forces among water molcols and when trying to turn water into stream you have to come over the third force that are in higher level of energy and its also because of hydrogen links among them that are in some substances including water and you have to break those links
2016-05-24 00:49:00 · answer #6 · answered by ? 4 · 0⤊ 0⤋
i woulda said it was the same amount
maybe look up the zero point, oh yeah triple point I guess
2007-01-17 07:05:02 · answer #7 · answered by kurticus1024 7 · 0⤊ 2⤋