During a change of state from liquid to solid (like in this problem, from liquid water to ice), the amount of heat that it is liberated is given by
[tex]Q=mL_f[/tex]
where
m is the mass of the substance
[tex]L_f[/tex] is the latent heat of fusion of the substance.
For ice, the latent heat of fusion is [tex]L_f=334 kJ/kg[/tex], while the mass of the water in this problem is m=88 kg. If we substitute these data into the equation, we find the amount of heat liberated:
[tex]Q=mL_f =(88 kg)(334 kJ/kg)=29392 kJ=29.4 MJ[/tex]
