Question

Question in details please help asap!!!?

2.0kg of water at 0 degree celsius is to be changed into ice at this temperature. The same mass of water now at 100 degree celsius is to be changed into steam at this temperature.
specific latent heat of fusion of water= 3.34 x10^5 J kg^-1.
specific latent heat of vaporization of water=2.26x10^6 J kg^-1
a)calculate the amount of energy needed to be removed from the water to freeze it.
b)calculate the amount of energy required by the water to vaporize it.
c)explain the difference between the values calculated in a) and b).

Answer 1

`a)` Just calculate the latent heat required for fusion of water into ice.

See the unit of latent heat says `J/(Kg)`

So, for given `2 Kg` the latent heat required to be removed will be `3.34*10^5 *2=6.68*10^5 J`

`b)` Similarly,for vaporization of the same amount of water heat energy required will be `2.26*10^6*2=4.52*10^6 J`

Now,value of `b` is more than `a` because,while changing the state from ice to water,we just need to weaken the cohesive force,but during conversion of water to gas,we need total breakage of the cohesive force(ideally) in order to allow,maximum kinetic energy,so the heat energy required is obviously higher in the later.