Some very hot rocks have a temperature of #420 ^o C# and a specific heat of #270 J/(Kg*K)#. The rocks are bathed in #36 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
Apr 26, 2017

The mass of the rocks is #=940.4kg#

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=420-100=320º#

# m_o C_o (DeltaT_o) = m_w H_w #

Heat of vaporisation of water

#H_w=2257kJkg^-1#

#C_o=0.27kJkg^-1K^-1#

#m_0 C_o*320 = m_w* 2257 #

#m_o*0.27*120=36*2257#

#m_o=(36*2257)/(0.27*320)#

#=940.4kg#