Question

The combustion of octane (C8H18) in oxygen proceeds as follows

2 C8H18(g) + 25 O2(g) ---> 16 CO2 (g) + 18 H2O(l)

How many moles of CO2are produced when 5.0 moles of octane, C8H18, is burned in 5.0
moles of oxygen?

Answer 1

Concepts and reason

Combustion is a process of the burning of hydrocarbons in the presence of oxygen with liberation of carbon dioxide gas and water. Number of moles of the substance is calculated by using the limiting reagent mole concept.

Fundamentals

Number of moles of the substance is the ratio of the mass to the molar mass of that substance. One mole of substance contains the Avogadro number of molecules in it.

Molar mass is the sum of the atomic masses of the individual atoms present in the molecule.

Limiting reagent: limiting reagent is a reactant, which consumes completely in the chemical reaction. Thus, quantity of the product depends on this limiting reagent.

Limiting reagent is determined from thebalanced chemical equation.

Givenbalanced chemical reaction:

From the balanced chemical equation, 2 moles of octane requires25 moles of oxygen for complete combustion.

From the given data, 5.0 moles of octane reacts with 5.0 moles of oxygen, but by balancedequation,5.0 moles of octane requires 63moles of oxygen.

Therefore, the oxygen is present in lesser amount to consume 5.0 mole of octane; therefore, quantity of product depends on the quantity of the oxygen.

Therefore, the limiting reagent is oxygen in this reaction.

Limiting reagent for the reaction is oxygen.

Ans:

Number of moles of produced is 3.2 mol.