1 litre of coffee at 80oC need to be cooled to 40oC. Assuming that all the ice melts and no heat is lost to the environment. Take the specific heat capacity of coffee to be 4200J/kgK, density of coffee to be 1000kg/m3 and latent heat of fusion of water to be 3.34 x 105 J/kg. You are required to:

Question

1 litre of coffee at 80oC need to be cooled to 40oC. Assuming that all the ice melts and no heat is lost to the environment. Take the specific heat capacity of coffee to be 4200J/kgK, density of coffee to be 1000kg/m3 and latent heat of fusion of water to be 3.34 x 105 J/kg. You are required to:
a)	Determine the heat lost by the coffee when ice is added and coffee cools to 40oC?
Solution:

b)	Determine the heat that is required to melt the ice and raise it temperature to 40oC?
=1 litre of coffee 80oC 
=Density of coffee is 1000kg/m3
=1 litre of coffee = density of coffee 1kg/m3
That mean, 1000 litre of coffee is equal to 1000kg/m3
 Q= me
=1000×3.34 x 105j/kg
=3.34 x 105=0.0000334j/kg
=1000×0.0000334j/kg
=0.0334kj
For that, the heat that is required to melt the ice and raise it temperature to 40oC is 0.0334kj

c)	Determine the amount of ice need to be added to 1 litre of the coffee to cools from 80oC to 40oC?
d)	If heat loss to the environment is not neglected, what is the relation between the diameter of cup and amount of ice needed to cools 2 litres coffee from 80oC to 40oC? Explain your answer.