6.1 For pure, liquid copper at its melting point, what is the Gibbs free energy of formation of a spherical crystalline cluster of solid (a nucleus of solid) of radius 5, 7, l A? Estimate the concentration of such nu.clei (r =: 5, 7, 10 A). For copper: Melting temperature = : 1083c Ys-1 =: 200 ergs/cm2 Heat of fusion =3120 cal/mol Assume that the molar volume is 7.0 cm3/mol for both solid and liquid.