Question

It takes 15 min to rise the temperature of a certain amount of water from 00 C to boiling point using a
heater and it takes 1 hour and 20 minutes more to convert all water to vapor. Find the latent heat of
vaporization of the water. (6mks)

Answer 1

ANSWER-:

Let the power delivered by the heater = P.

Heat supplied in 15 minutes = 15P = Q  

​Heat supplied in 1 hour and 20 minutes = 80P = Q  

 =mcΔT=m(1)(100)=100m  

​ =mL L is the latent heat of vaporization.

i.e. dividing Q  

and Q  

80

15=L 100

​   i.e. L=533.33 cal.