C. The energetics of solute movement Diffusion is the spontaneous movement of material from a region of high concentration to a region of low concentration %The free-energy change during diffusion of nonelectrolytes depends on the concentration grdient The free-energy change during diffusion of electrolytes depends on the electrochemical grdient.C. The energetics of solute movement: ❖Diffusion is the spontaneous movement of material from a region of high concentration to a region of low concentration. ❖The free-energy change during diffusion of nonelectrolytes depends on the concentration grdient. ❖The free-energy change during diffusion of electrolytes depends on the electrochemical grdient