# Physics latent heat problem

Watch
Announcements
#1
The specific latent heat, L of a material is defined as the amount of
enegry
needed to change the phase of 1kg of material without any change to temperature.
(a) how much heat is needed to melt completely 12kg of ice at 0 degrees ? Assume the latent heat of fusion of ice is 335 J/kg.
(b) how much heat is required to change 1.3kg of water at 20 degrees celcius at 100 degrees celcius if the specific heat capacity of water is 4200 J Kg K and the specific latent heat at 100 degrees celcius is 2257 kJ/Kg?

I know how to answer the first q I am stuck on the second part
help is appreciated
0
9 months ago
#2
I'm assuming thats specific latent heat of vaporisation, and the water is changing to steam.

So you need to calculate how much energy is needed to heat the water to 100 deg from 20 deg. Use the E=mc(t2-t1) Where m is mass, c is specific heat capacity, and t is the temperatures. The further heat must be applied to change the water to steam which is E=mL, where L is the specific latent heat of vaporisation. The amount of energy required to change the water to steam is how much energy it take to heat the water to the desired temp plus the energy required to change its state, therefore it is both of these energies added together.

Does that make sense?
0
#3
(Original post by Roasted Potato)
I'm assuming thats specific latent heat of vaporisation, and the water is changing to steam.

So you need to calculate how much energy is needed to heat the water to 100 deg from 20 deg. Use the E=mc(t2-t1) Where m is mass, c is specific heat capacity, and t is the temperatures. The further heat must be applied to change the water to steam which is E=mL, where L is the specific latent heat of vaporisation. The amount of energy required to change the water to steam is how much energy it take to heat the water to the desired temp plus the energy required to change its state, therefore it is both of these energies added together.

Does that make sense?
Thankyou for the help, great explanation !
0
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

#### Do you have the space and resources you need to succeed in home learning?

Yes I have everything I need (398)
56.29%
I don't have everything I need (309)
43.71%