$2.$ The adsorption of a certain substance, X$,$ follows a Langmuir isotherm. Saturation coverage of the material is $8\backslash$times $10-10$ mol$/$cm$2$ and $=5\backslash$times $107$ cm$3/$mol $($assuming ai $=$ Ci$).$ At what concentration of X will the electrode surface be half covered? Sketch the adsorption isotherm of the substance. At what concentrations of X will the linearized isotherm be valid to ~$1\%?$ Under linearized conditions and taking D $=10-5$ cm$2/$s$,$ how long after immersion will be required for the surface of a plane electrode to attain half of the equilibrium coverage? How long will be required to attain half of equilibrium coverage if the solution is stirred and m $=10-2$ cm$/$s$?$