Some very hot rocks have a temperature of #250 ^o C# and a specific heat of #80 J/(Kg*K)#. The rocks are bathed in #250 L# of boiling water. If the heat of the rocks completely vaporizes the water, what is the minimum combined mass of the rocks?

1 Answer
May 9, 2017

The mass of the rocks is #=47020.8kg#

Explanation:

The heat transferred from the rocks to the water, is equal to the heat used to evaporate the water.

For the rocks #DeltaT_o=250-100=150º#

Heat of vaporisation of water

#H_w=2257kJkg^-1#

The specific heatof the rocks is

#C_o=0.08kJkg^-1K^-1#

The mass of water is #m_w=144kg#

# m_o C_o (DeltaT_o) = m_w H_w #

#m_o*0.08*150=250*2257#

The mass of the rocks is

#m_o=(250*2257)/(0.08*150)#

#=47020.8kg#