Consider an isothermal cloud of coal particles that contains $50\%$ by weight

$50\backslash$mu m particles and $50\%$ by weight $100\backslash$mu m particles flowing in a stream of hot, isothermal gas containing $20\%$ excess oxygen. Determine the particle burnout time based on $99\%$ burnout and plot the particle mass divided by the initial particle mass as a function of time. Use an effective char kinetic rate constant of $0\mathrm{.}5$ gO$2/($cm$2$ s $$ atmO$2),$ a char density of $0\mathrm{.}8$ g$/$cm$3,$ and an initial oxygen pressure of $0\mathrm{.}1$ atm. Repeat for $100\backslash$mu m particles and compare the burnout times based on $99\%$ burnout.