for the solidification of pure gold, calculate the critical radius (r*) and the activation freeenergy (*). assume homogeneous nucleation conditions. the values of the latent heat of fusion and the surface free energy are -1.16x109 j/m3 and 0.132 j/m2, respectively. the degree of supercooling is 30 k and the melting point of gold is 1064 oc.