Question

Calculate the heat energy released when 10.7 g of liquid mercury at 25.00 °C is converted to solid mercury at its melting point.

Answer 1

Initial temperature (T_i) = 25.00 ^oC

Final temperature (T_f) = Melting point of mercury = - 38.83 ^oC

Temperature difference, $\Delta T$ = (T_f - T_i) = ( - 38.83 ^oC - 25.00 ^oC) = - 63.83 ^oC

Mass of mercury (m) = 10.7 g

Specific heat capacity of mercury (s) = 0.140 J/g.^oC

Now, heat energy released = m x s x $\Delta T$                 

                                            = 10.7 g x 0.140 J/g.^oC x (- 63.83 ^oC)

                                            = - 95.6 J          (the negative sign implies that the heat is released)