Question

Calculate the heat energy released when 19.6 g of liquid mercury at 25.00 °C is converted to solid mercury at its melting point. Answer in KJ

Answer 1

eat capacity for Hg(l) = 28j/mole-K
melting point            = 234.32K
enthalpy of fusion       = 2.29kj/mole
atomic mass of Hg = 200.6g/mole
no of moles of Hg = 19.6/200 = 0.098 moles
234.32K liquid to 25C(298K) liquid
Q = 0.098*28*(298-234.32)
= 0.098*28*63.68
= 174.75j
234.32K liquid to 234.32K solid
Q = 0.098*2.29
= 0.22344kj/mole
total heat energy = 0.17475+0.22344
                  = 0.39819 kj >>>> answer