Consider the general combustion of a gaseous hydrocarbon in a eudiometer tube: . If represents the v — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question
Question
Consider the general combustion of a gaseous hydrocarbon $C_xH_y$ in a eudiometer tube: $C_xH_y(g) + (x + y/4)O_2(g) \rightarrow xCO_2(g) + y/2 H_2O(l)$. If $V_1$ represents the volume contraction observed upon cooling the mixture to room temperature, and $V_2$ represents the further contraction observed upon passing the residual gas through a concentrated $KOH$ solution, which of the following theoretical relationships are correct?
💡 Solution & Explanation
Statement A is true; $KOH$ is a specific absorbent for acidic gases like $CO_2$, so $V_2 = V_{CO_2}$. Statement B is true; $V_1 = (\text{Volume of Reactants}) - (\text{Volume of gaseous Products}) = [V + V(x + y/4)] - Vx = V(1 + y/4)$, assuming $H_2O$ is liquid. Statement C is true; based on stoichiometric coefficients, $O_2$ needed is $V(x+y/4)$. Statement D is false; $KOH$ does not absorb unreacted oxygen gas ($O_2$ requires alkaline pyrogallol).