Evaluate a uniform pseudo-first-order gas decomposition defined broadly by the stoichiometric reacti — Chemical Kinetics Chemistry Question
Question
Evaluate a uniform pseudo-first-order gas decomposition defined broadly by the stoichiometric reaction $A(g) \rightarrow B(g) + 2C(g)$ inside a perfectly sealed, constant-volume chamber. Assuming the sole starting gas is $A$ with baseline pressure $P_0$, and the compound total pressure continuously reads $P_t$, which of the specified relations accurately portray the internal kinetic reality?
💡 Solution & Explanation
Tracking stoichiometry: $P_t = (P_0 - x) + x + 2x = P_0 + 2x$, isolating $x = (P_t - P_0)/2$. Thus $P_A = P_0 - x = P_0 - (P_t - P_0)/2 = (3P_0 - P_t)/2$. This makes A correct, and B follows correctly directly plugging into $k$. C is true as 1 mole gas gives 3 total moles, so ending pressure triples $P_0$. D is false because product $B$ pressure is uniquely $x$, which rigorously evaluates to $(P_t - P_0)/2$, not merely $(P_t - P_0)$.