500 mL of a hydrocarbon gas burnt in excess of oxygen, gave 2500 mL of CO7 and 3000 mL of wat

step 1 In this problem I can write the reaction as CX, HY plus x plus y by 4O2 will give X CO2 plus Y b

500 mL of a hydrocarbon gas burnt in excess of oxygen, gave...

$500 \mathrm{~mL}$ of a hydrocarbon gas burnt in excess of oxygen, gave $2500 \mathrm{~mL}$ of $\mathrm{CO}_{7}$ and $3000 \mathrm{~mL}$ of water vapour (at constant $\mathrm{T}$ and $\mathrm{P}$ ). The formula of the hydrocarbon is (a) $\mathrm{C}_{3} \mathrm{H}_{6}$ (b) $\mathrm{C}_{2} \mathrm{H}_{4}$ (c) $\mathrm{C}_{5}{ }^{3} \mathrm{H}_{12}^{6}$ (d) $\mathrm{CH}_{4}$

$500 \mathrm{~mL}$ of a hydrocarbon gas burnt in excess of oxygen, gave $2500 \mathrm{~mL}$ of $\mathrm{CO}_{7}$ and $3000 \mathrm{~mL}$ of water vapour (at constant $\mathrm{T}$ and $\mathrm{P}$ ). The formula of the hydrocarbon is
(a) $\mathrm{C}_{3} \mathrm{H}_{6}$
(b) $\mathrm{C}_{2} \mathrm{H}_{4}$
(c) $\mathrm{C}_{5}{ }^{3} \mathrm{H}_{12}^{6}$
(d) $\mathrm{CH}_{4}$

Key Concepts

Combustion Reaction

A combustion reaction for a hydrocarbon involves its reaction with oxygen to produce carbon dioxide and water. In such reactions, each carbon atom becomes part of a CO2 molecule, and every two hydrogen atoms form a water molecule. This stoichiometric relationship is fundamental when analyzing the products to determine the composition of the hydrocarbon.

Avogadro's Law

Avogadro's Law states that equal volumes of gases, under the same conditions of temperature and pressure, contain an equal number of moles. This allows us to use the volumes of gaseous products directly to infer the mole ratios of the species involved, which is essential in solving problems where only the gas volumes are provided.

Balancing Chemical Equations

Balancing chemical equations is necessary to satisfy the law of conservation of mass. For hydrocarbon combustion, this involves ensuring that the number of carbon atoms from the fuel ends up exactly as many CO2 molecules, and the hydrogen atoms are appropriately divided into H2O molecules. Such balancing allows one to set up proper stoichiometric relationships between reactants and products.

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on the mole ratios derived from the balanced equation. In problems involving gases, stoichiometry often leverages the direct proportionality between volume and number of moles (as per Avogadro's Law), enabling the use of measured gas volumes to determine the molecular formula of the reactant.

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