Mar 6th 2017, 07:15 AM
Join Date: Mar 2017
Needs help with my homework
5 liters of water at 70˚c need to cooled to 50˚c.
Specific heat capasity of water is 4200J/kgK
Latent of heat of fusion of water is 3.34 x 10e5 J/kg
and the water density is 2000kg/m3
Determine the heat lost by the water when ice is added as the water cools to 50˚c
Ans = 420 KJ
Determine the heat required to melt the ice and raise the temp to 50˚c
Q2 = Heat needed to melt the ice and raise the temperature to 50˚C
Ans = 5.44 x 10e5m J
Determine the amount of ice to be added to the water to cools it from 70˚c to 50˚c
Since there is no heat loss to the environment, it can be concluded that
Ans = 0.772 kg
The question asked, if the heat to the environment is not neglected, what is the relation between the diameter of the mug and the amount of ice needed to cools 7 liters of water from 70˚c to 50˚c.
I'm stuck, I know that the relation is time, needed to cools it naturally and by adding ice but I can't find any formula to relates time in it.
Thanks in advance