Question

How much heat is evolved in converting 1.00 mol of steam at 130.0 C to ice at -50.0 C? The heat capacity of steam is 2.01 J/(g⋅C) and of ice is 2.09 J/(g⋅C).

Answer 1

1 mol = 18 g of H2O

This is done in steps

Heat evolved   for ccooling steam from 130 to 100 C

   =   mass x specific heat x temp change = 18 x 2.01 x ( 130-100) = 1085.4 J

Heat evolved during condesation of steam to water at 100C

       = mass of steam x enthalphy of condesation = 18 x 2257   = 40626 J

Heat evolved during cooling water from 100 to 0 C

= mass x specific heat x temp change = 18 x 4.184 x 100 =7531.2 J

heat required for phase change of liquid water to solid ice at 0C = mass x enthalphy of fusion

               = 18 x 334 = 6012 J

heat required to cool ice at 0 C to - 50 C

         = mass x specific heat of ice x temp change = ( 18 x 2.09) x ( 50) = 1881 J

combining all heats we get = 57135.6 Joules = 57.135 KJ