$($a$)$ Limestone is burnt in a kiln where conversion is $70\%$ :

$CaC{O}_3$longrightarrowCaO$+C{O}_2$

$($i$)$ What is the composition $($mass$\%)$ of the solid withdrawn from the kiln?

$($ii$)$ How many $kg$ of $C{O}_2,$ are produced per $kg$ of $CaC{O}_3$ fed?

Atomic Weights: $Ca-40$;$C-12$;$0-16$

$(10$ marks$)$

$($b$)$ When pure carbon is burnt in air, some of it oxidizes to $C{O}_2,$ and some to $CO.$ If the molar ratio of $N_2,$ to $O_2,$ is $7\mathrm{.}18$ and the ratio of $CO$ to to $C{O}_2$ is $2\mathrm{.}0$ in the product gas, what is the per cent excess air used?

The exit gases contain only $N_2,O_2,CO$ and $C{O}_2$

Assume air is $79$mole$\%$ nitrogen and $21$ mole$\%$ oxygen.

$(15$ marks$)$

Mid Term $2016$

$2.$ A fuel consisting of $30\%$ methane and $70\%$ ethane is to be burned in $20\%$ excess oxygen. Determine the moles of air required per mole of fuel. $($Assume air is $21$mole$\%$ oxygen and $79$mole$\%$ nitrogen$).$

marks