Past exam of the chemistry course of the year 3 of the natural sciences course of the University of Cambridge / 2022 / Paper 4 / 64 / a / Solution

For cubes of side $\ell$, total area divided by total mass is $S=6/(\rho \ell )$, independently of how many cubes share the $100\mathrm{g}$ sample. With $S=5000{\mathrm{m}}^2\mathrm{k}{\mathrm{g}}^{-1}$ and $\rho =2330\mathrm{kg}{\mathrm{m}}^{-3}$,This assumes accessible external faces, negligible contact-area losses and equally sized nonporous cubes; BET adsorption can also count accessible internal surface in a porous powder.