(a) for the solidification of iron, calculate the critical radius r* and the activation free energy δg* if nucleation is homogeneous. values for the latent heat of fusion and surface free energy are –1.85 × 109 j/m3 and 0.204 j/m2, respectively. use the supercooling value δt = 274 k, and the melting point of iron is 1538°c. critical radius, r* = nm activation free energy δg* = j
(b) now calculate the number of atoms found in a nucleus of critical size. assume a lattice parameter of 0.292 nm for solid iron at its melting temperature. number of atoms for critical size = atoms/critical nucleus

Agas contained within a piston-cylinder assembly e end nation about same energy states, 1 and 2, where pi 10 bar, v undergoes two processes, a and b, between the sam 0.1 m3, ui-400 kj and p2 1 bar, v2 1.0 m2, u2 200 kj: process a: process from 1 to 2 during which the pressure- volume relation is pv constant process b: constant-volume process from state 1 to a pressure of 2 bar, followed by a linear pressure-volume process to +20 0 state 2 kinetic and potential energy effects can be ignored. for each of the processes a and b, (a) sketch the process on p-v coordinates, (b) evaluate the work, in kj, and (c) evaluate process the heat transfer, in kj