Question

The latent heat of vaporization of water is 2260 J/g. How much energy is released when 100 grams of water condenses from vapor at $$100^\circ C$$?

Answer 1

Hint: In order to solve the question, we will use the relation between energy, latent heat of vaporization of water and mass. Then we use the formula to find the energy used in converted liquid water into water vapour and then the energy will come out we will convert it from joules to kilojoules.

Formula used:
$Q = {L_V} \times m$
$Q$ represents energy.
${L_V}$ represents the latent heat of vaporization of water
$m$ represents the mass.

Complete step by step solution:
In the question we are given the latent heat of vaporization of water and we have to find the how much energy is released when the water is converted from liquid to vapour at a certain temperature
The latent heat of vaporization of water = 2260 J/g
Mass of water = 100 g
Temperature at which process is happening = $100^\circ C$
The relation between energy, latent heat of vaporization of water and mass can be used in this question in order to find the energy which is released
$Q = {L_V} \times m$
Now we will substitute the values of latent heat of vaporization of water and mass
$Q = 2260\dfrac{J}{g} \times 100g$
Unit of Gram will cut off as they are in numerator and denominator
$Q = 226000{\text{ J}}$
Now we will convert energy from joules to kilojoules
1 KJ= 1000 KJ
So, the energy is Q= 226 KJ
Therefore, $226 KJ$ energy is released, when 100 grams of water condenses from vapor at $100^\circ C$.

Note:
Many of the people will may confuse why the temperature is given in the question and what it represents so specifically $$100^\circ C$$ is given in the question as the process of converting from liquid water to the water vapour can only happen at that temperature so if $$100^\circ C$$ the change of state will not take place.