Question

Given, 3000cc of oxygen was burnt with $600cc$ of ethane. Calculate the volume of the residual mixture at room temperature.
$2{C_2}{H_6} + 7{O_2} \to 4C{O_2} + 6{H_2}O$

Answer 1

Combustion is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion does not always result in fire, but when it does, a flame is a characteristic indicator of the reaction.

Complete step by step answer:
In complete combustion, the reactant burns in oxygen and produces a limited number of products. When a hydrocarbon burns in oxygen, the reaction will primarily yield carbon dioxide and water. When elements are burned, the products are primarily the most common oxides.
In the given question, there is a complete combustion of the ethane in the presence of excess oxygen such that some amount of oxygen remains as a leftover whiles all the ethane burns completely releasing carbon dioxide and water as the product. The reaction that occurs here is as follows:
$2{C_2}{H_6} + 7{O_2} \to 4C{O_2} + 6{H_2}O$
In the above reaction, 1 mole of ethane requires $\dfrac{7}{2}moles$ of oxygen to give $2moles$ of $C{O_2}$ and $3moles$ of ${H_2}O$ . The reaction can be written as follows:
${C_2}{H_6} + \dfrac{7}{2}{O_2} \to 2C{O_2} + 3{H_2}O$
$600cc$ of ethane reacts with = $600 \times \dfrac{7}{2} = 2100cc$ of ${O_2}$
As per the question, we have an excess of $3000cc$ of ${O_2}$ and the amount of oxygen consumed is only $2100cc$ .
Thus, the residual oxygen is $(3000 - 2100)cc = 900cc$

Note:
Incomplete combustion will occur when there is not enough oxygen to allow the fuel to react completely to produce carbon dioxide and water. It also happens when the combustion is quenched by a heat sink, such as a solid surface or flame trap. As is the case with complete combustion, water is produced by incomplete combustion; however, carbon, carbon monoxide, and hydroxide are produced instead of carbon dioxide.