Solid carbon at 25^∘ C is burned with a stoichiometric...

Solid carbon at $25^{\circ} \mathrm{C}$ is burned with a stoichiometric amount of air which is at 1 atm pressure and $25^{\circ} \mathrm{C}$. Determine the number of moles of $\mathrm{CO}_{2}$ formed per $\mathrm{kmol}$ of carbon when only $\mathrm{CO}_{2}, \mathrm{CO}, \mathrm{O}_{2},$ and $\mathrm{N}_{2}$ are present in the products and the products are at 1 atm and $727^{\circ} \mathrm{C}$.

Key Concepts

Mole Balances

Mole balance involves applying the conservation of mass to chemical reactions by equating the total number of moles of each element on the reactants side to that on the products side. This concept is essential in combustion calculations for determining the number of moles of various products formed per unit of fuel burned, ensuring that all atoms are accounted for in the analysis.

Thermodynamic Equilibrium in Combustion

At elevated temperatures, combustion reactions often do not go to completion in the classical sense and can reach a state of equilibrium where multiple oxidation products coexist. Understanding chemical equilibrium is crucial in predicting the final composition of the products, as temperature and pressure conditions dictate the distribution between products like carbon dioxide and carbon monoxide.

Air Composition

Air is a mixture of gases, primarily oxygen and nitrogen, with oxygen constituting about 21% by volume and nitrogen approximately 79%. When performing combustion calculations, it is essential to account for the inert nitrogen introduced along with oxygen. This composition determines the molar ratios and influences the overall balance in combustion reactions.

Stoichiometric Combustion

This concept involves burning a fuel with exactly the amount of oxidant required such that no excess oxygen remains. In the context of combustion reactions, it means precisely matching the fuel with the oxygen from the air to ensure complete consumption of the available oxygen under ideal conditions, while also recognizing that at high temperatures, even stoichiometric mixtures may produce multiple oxidation products.

Reaction Stoichiometry

Reaction stoichiometry refers to the quantitative relationship between reactants and products in a chemical reaction. In combustion processes, it is used to set up mole balance equations that relate the amounts of fuel, oxidant, and the resulting products. This helps in determining how many moles of each product, such as carbon dioxide and carbon monoxide, are formed based on the input amounts.

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