Question

Constants for mercury at 1 atm
heat capacity of Hg(l)	28.0 J/(mol·K)
melting point	234.32 K
enthalpy of fusion	2.29 kJ/mol

Calculate the heat energy released when 12.0 g of liquid mercury at 25.00° C is converted to solid mercury at its melting point.

Energy: ?KJ

Answer 1

atomic mass of Hg = 200.5920g/mole

no of moles of Hg   =W/G.A.Wt

                               = 12/200.5920   = 0.0598 moles

(-38.60)234.32K liquid to 25⁰C(298.15K) liquid

Q1   = ncT

          = 0.0598*28*(298.15-234.32)   = 106.87J   = 0.10687KJ

234.32K liquid to 234.32 solid

Q2    =n* heat of fustion

        = 0.0598*2.29   = 0.137KJ

total heat = 0.10687+0.137   = 0.2439KJ   >>>>>answer