Question

A refrigerator converts 100g of water at 20°C to ice at -10°C in 35 minutes.
Calculate the average rate of heat extraction in terms of watts.
Given :
Specific heat capacity of ice = 2.1 Jg-1°C~1.
Specific heat capacity of water = 4.2 J g1°C~1.
Specific Latent heat of fusion of ice = 336 J g-1
14​

Answer 1

Answer:

21

Explanation:

heat extracted in 3 steps

step1: 20 degree water to 0 degree water->

          heat =mass *c*change in temp

                     100*4.2*20=8400

step2:0 degree water to 0 degree ice ->

           heat = mass* Latent heat

                      100*336=33600

step3: 0 degree ice to -10 degree ice ->

         heat = mass *c* change in temp

                    100*2.1*10=2100

therefore net heat =44100

net time= 35 min *60 sec

therefore power =work/time

                              44100/(35*60)

                             =21