Chemistry - Eudiometry Question with Solution | TestHub

Question Explanation: Finding a hydrocarbon's formula from product volumes.

Concept: Gay-Lussac's Law of Gaseous Volumes.

Solution: The ratio of volumes of gaseous reactants and products is the same as their stoichiometric ratio. By comparing the volume of the hydrocarbon to the volumes of ${\mathrm{CO}}_2$ and water vapor, we can find its molecular formula.

Calculation: Reaction: ${\mathrm{C}}_{\mathrm{x}}{\mathrm{H}}_{\mathrm{y}}(\mathrm{g})+\left(\mathrm{x}+\frac{\mathrm{y}}{4}\right){\mathrm{O}}_2(\mathrm{g})\to {\mathrm{xCO}}_2(\mathrm{g})+\frac{\mathrm{y}}{2}{\mathrm{H}}_2\mathrm{O}(\mathrm{g})$.

Given volumes: ${\mathrm{V}}_{{\mathrm{C}}_{\mathrm{x}}{\mathrm{H}}_{\mathrm{y}}}=2\mathrm{L},{\mathrm{V}}_{{\mathrm{CO}}_2}=8\mathrm{L},{\mathrm{V}}_{{\mathrm{H}}_2\mathrm{O}}=10\mathrm{L}$. From the volume ratios:

 

 

For Carbon: $1V_{C_x{H}_y}=x{V}_{C{O}_2}\Rightarrow \frac{1}{2}=\frac{x}{8}\Rightarrow x=4$

 

 

For Hydrogen:

So, $1V_{C_x{H}_y}=\frac{y}{2}{V}_{H_{2}O}\Rightarrow \frac{1}{2}=\frac{y}{2}.10\Rightarrow 5y=1\Rightarrow y=10$

 

.The hydrocarbon is $C_4{H}_{10}$.

 

Final Answer: option (c)