Cryogenic gases are often stored in double-walled, spherical containers. The space between the two walls is evacuated so that all heat transfer between the walls occurs via radiation. Assume liquid oxygen is being stored in the inner container ( \(10 \mathrm{~m}\) in diameter) at a temperature of \(95 \mathrm{~K}\). The outer shell of the container is held at \(280 \mathrm{~K}\), on average, and is \(15 \mathrm{~m}\) in diameter. If the walls of the container are opaque, diffuse, gray surfaces with emissivities of 0.05,

a. What is the net radiative exchange between the walls of the vessel?

b. How much oxygen will be lost via evaporation? \(\left(\Delta H_{v a p}=6.82 \mathrm{~kJ} / \mathrm{mol}\right)\)

c. Why store the material in spherical containers?