Question

How long will it take 2kg of water to boil in a copper pot that weight .650 kg Given that the stove can produce 1000 W? During the boiling you can assume that 20% of the energy is lost. The initial Temperature was 75 Kelvins.

Answer 1

Power of the stove = 1000W = 1000 J/s

Initial temperature = 75K

Final Temperature = boiling water temperature = 100 degree celsius = 100+273K/1 degree Celsius = 373K

delta T (final temperature - initial temperature) = (373-75) = 298K

Now, heat is transfered from stove to pot to water

Qstove->Q pot->Q water

Q water = mass of water * heat of vaprozation of water * delta T

Q water = 2000g*75.3J/K mol* 298K* 1mol water/18g water (1 mol of water has 18g)

Q water =2493266.666666667 J, heat needed to boil water = 249.32kJ

heat transfered from stove at the rate of 1000J per second to pot to water, copper pot is good conductor of electricity will transfer heat directly to water

energy loss happens during boiling and hence can be ignored to calculate the time needed for water to boil.

time needed to transfer heat = 2493266.666666667J/1000J/s = 2493.266666666667sec = 41 minutes

***Please confirm the heat of vaporization of water****Please validate this answer from Physics expert****