26.7 A spherical ball of solid, nonporous naphthalene, a "moth ball', is suspended in still air. The naphthalene ball slowly sublimes, releasing the naphthalene into the surrounding air by molecular diffusion-limited process. Estimate the time required to reduce the diameter from 2 to 0.5cm when the surrounding air is at 347K and 1.013105Pa. Naphthalene has a molecular weight of 128g/mol, a solid density of 1.145g/cm3, a diffusivity in air of 8.19106m2/s, and exerts a vapor pressure of 5 Torr (666 Pa) at 347K