[A-level]Latent Heat Question, Help

  • Thread starter Thread starter Boogeyman
  • Start date Start date
  • Tags Tags
    Heat
Click For Summary
SUMMARY

The discussion centers on calculating the energy required to evaporate a specific volume of water, given the specific latent heat of vaporization at 28°C, which is 2.3 x 106 J/kg. The volume of water to be evaporated is 1.2 x 1012 m3, and the density of water is 1 x 103 kg/m3. The correct approach involves calculating the mass of water using the formula mwater = ρV, leading to the final energy calculation of 2.67 x 1018 J.

PREREQUISITES
  • Understanding of specific latent heat, particularly for water.
  • Knowledge of the relationship between mass, density, and volume (m = ρV).
  • Familiarity with energy calculations in thermodynamics.
  • Basic algebra for manipulating equations.
NEXT STEPS
  • Study the concept of specific latent heat and its applications in thermodynamics.
  • Learn how to calculate mass from volume and density using the formula m = ρV.
  • Explore energy transfer during phase changes, focusing on evaporation and condensation.
  • Investigate real-world applications of latent heat in meteorology and environmental science.
USEFUL FOR

Students studying physics or environmental science, educators teaching thermodynamics, and anyone interested in the principles of energy transfer during phase changes.

Boogeyman
Messages
75
Reaction score
0

Homework Statement


The specific latent heat of vaporization of water at 28[tex]\circ[/tex]C is 2.3 x 106JKg-1. It has been estimated that 1.2 x 1012 m3 of water is evaporated per day from the Earth's surface.

Given that the density of water is 1 x 103 kgm-3calculate the energy required to evaporate this volume of water.



The Attempt at a Solution



I'm thinking since the water is just evaporating and not boiling, the energy needed would be the heat required to just evaporate the water:

EH=mwater x latent heat
=2.67 x 1018J

But this is wrong. I realize I have not used the density of water but I do not know how to apply it. Is this question asking me to find the increase in internal energy?

In any case the volume of water is 1.02 x 109m3.
 
Physics news on Phys.org
Boogeyman said:
EH=mwater x latent heat

What did you use for the mass of water? You need to find the mass using mwater=ρV
 
rock.freak667 said:
What did you use for the mass of water? You need to find the mass using mwater=ρV

:frown:

I cannot believe I made such a silly mistake. For some reason I always saw the volume as the mass.

Anyways I got the correct answer now. Thanks.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 11 ·
Replies
11
Views
5K
Replies
3
Views
5K
Replies
21
Views
3K
  • · Replies 3 ·
Replies
3
Views
6K
Replies
3
Views
3K
Replies
9
Views
4K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K