The concentration of Cl^- in the thin layer remains constant throughout the experiment. Estimate the average penetration depth of chlorine ions in the ice after 10 seconds and after 1000 seconds. The average size of the crystallites is 0.1 micrometers, and the width of the grain boundaries is approximately 5 nm. Assume that the diffusivity of chlorine anion in single-crystal ice is 10^-3 micrometer²/s and that the diffusivity along grain boundaries is two orders of magnitude faster.