why is latent heat of vaporization higher than latent heat of fusion?

Question

why is latent heat of vaporization higher than latent heat of fusion? i don't get it. i've googled it, but everything is way too complex for me to understand clearly.

how do you calculate the energy need to find the following: 1) to melt 23g of water.
2) turn 36g water to steam.
for 1) is it just 80 calories?
and 2) 540 calories?

Answer 1

OK, so start with the idea that you have different phases of a molecule, for this example we'll use H2O. Water has three distinct phases: ice (solid), water (liquid) and steam (gas). To get from ice to steam you have two phase transitions; the transition from ice to water and then the transition from water to steam. In each case you are going from a more ordered state to a more chaotic state (think of molecules of H2O in ice as "frozen" into place; now picture hyperactive molecules of water bouncing all over the place as steam; water can be somewhere between these extremes). OK, so the latent heat of fusion is the energy needed to seperate the molecules of H2O in ice into a puddle of water at the same temperature (zero degrees C). Now heat this same water up until it's almost boiling; the latent heat of vaporization is the energy needed to make water at 100 degrees C really go crazy and go from the liquid to the gas phase. You can see that a molecule of H2O that is steam has tons more energy than a virtually motionless molecule of H2O that is crystillized as ice. That is why the latent heat of vaporization is much much greater than the latent heat of fusion. Think about it this way and you should be good to go. Hope this helps!

Answer 2

In thermochemistry, latent heat is the amount of energy in the form of heat released or absorbed by a substance during a change of phase (i.e. solid, liquid, or gas), - also called a phase transition. Latent heat of fusion is the process whereby heat is absorbed without a change in temperature or melting point of a substance. Latent heat of vaporisation is the absorption of heat or boiling point of a substance without any change in temperature. More energy is required in latent heat of vapourisation because the molecules are broken free of their strong bonds in liquid to become air, rather than only becoming weaker to form a liquid in latent heat of fusion. The equation for latent heat is: Q = mL where: Q is the amount of energy required to change the phase of the substance, m is the mass of the substance, L is the specific latent heat for a particular substance. In other words, specific latent heat is found when energy is divided by mass. For example: water: Latent Heat of Fusion, 334J/g at 0 Degree Celcius Latent heat of vapourisation, 2272J/g at 100 Degree Celcius More information is available at the following website.

Answer 3

The latent heat of fusion refers to the melting point of a substance (changing states from solid to liquid).
The latent heat of vaporization refers to a substance's boiling point (changing states from liquid to gas).
So, thinking of water, the melting point is 0C and boiling point is 100C. This is consistent for all substances, boiling point is always higher than melting point.

The more heat you add to a substance causes the molecules to move faster and faster. This causes both melting as the molecules move fast enough to go from solid to liquid, and more energy in the form of heat is required to further speed up the molecules enough to get a substance to its boiling point.

Answer 4

I am not sure but I always explained it to myself by recognizing that the distance between the atoms in a chunk of ice is not much different than the distance between the atoms of liquid water. The molecules of vapor are very much farther apart than they were when they were liquid.

Answer 5

this is bacause latent heat of fusion involved the weaken of bonds from solid to liquid while in latent heat of vapourisation involved the breaking of bonds from liquid to gas at the same temperature and ,uch energy is rrequired to do this