The heat released by the water when it cools down by a temperature difference [tex]\Delta T[/tex] is
[tex]Q=mC_s \Delta T[/tex]
where
m=432 g is the mass of the water
[tex]C_s = 4.18 J/g^{\circ}C[/tex] is the specific heat capacity of water
[tex]\Delta T =71^{\circ}C-18^{\circ}C=53^{\circ}[/tex] is the decrease of temperature of the water
Plugging the numbers into the equation, we find
[tex]Q=(432 g)(4.18 J/g^{\circ}C)(53^{\circ}C)=9.57 \cdot 10^4 J[/tex]
and this is the amount of heat released by the water.
