USE ALL VALUES GIVEN A solid naphthalene sphere is initially $10$ mm in diameter is suspended in still air.

Calculate how long it will take for the sphere diameter to be reduced to $5$ mm$.$ State

any assumptions you make in your calculations.A solid naphthalene sphere is initially $10mm$ in diameter is suspended in still air.

Calculate how long it will take for the sphere diameter to be reduced to $5mm.$ State

any assumptions you make in your calculations.

Data:

Naphthalene Properties

Molecular Mass

Density

D$.$ diffusion coefficient in air

Vapour pressure at $288K$

System Properties

Temperature

$-,288K$

Pressure

$,1\mathrm{.}013{10}^5\frac{N}{m^2}$

Useful formulae

The mass transfer coefficient, $k,$ for a sphere of diameter $d$ can be described

by $k=\frac{2D}{d}$

The formula for the area of a sphere of radius $r$ is $4r^2$

The formula for the diameter of a sphere of radius $r$ is $\frac{4}{3}{r}^3$