Question

Ultimate analysis of an MSW sample (mass fractions, % by weight): C = 48, H = 6, O = 35, N = 6, Ash = 5. For burning 1 kg of this MSW (air contains only O$_2$ and N$_2$), the maximum CO$_2$ emitted is ________________ (in kg, rounded off to three decimals).

Hint:

When asked for \textbf{maximum} CO$_2$, send \emph{all} fuel carbon to CO$_2$. The oxygen present in the fuel does not reduce this theoretical maximum—it only reduces the external O$_2$ demand.

Answer 1

Correct Answer: 1.7

Step 1: Determine available carbon in 1 kg waste.
Mass of carbon $=0.48\times 1\ \text{kg}=\boxed{0.48\ \text{kg C}}$.
Moles of C $=\dfrac{0.48}{12}\ \text{kmol}=\boxed{0.040\ \text{kmol C}}$.
Step 2: ``Maximum CO$_2$'' assumption.
All C $\Rightarrow$ CO$_2$ (no CO/soot). So moles of CO$_2 = $ moles of C $=0.040$ kmol.
Step 3: Convert moles of CO$_2$ to mass.
Mass CO$_2 = 0.040\times 44=\boxed{1.76\ \text{kg}}$. Final Answer:\fbox{1.760 kg}