Final answer:
The true expression for the reaction N₂O₄(g) ⇌ 2 NO₂(g) is B. -∆[N₂O₄]/∆t = ∆[NO₂]/∆t, correlating the rates of decomposition and formation based on stoichiometry.
Step-by-step explanation:
The correct expression for the given reaction N₂O₄(g) ⇌ 2 NO₂(g) is B. -∆[N₂O₄]/∆t = ∆[NO₂]/∆t. This expression signifies that the rate of decomposition of dinitrogen tetroxide (N₂O₄) is equal to the rate of formation of nitrogen dioxide (NO₂) when we account for their stoichiometry. Since the reaction shows a ratio of 1 mole of N₂O₄ producing 2 moles of NO₂, the rate at which NO₂ is formed is twice the rate at which N₂O₄ is consumed. Hence, we express this by saying for every unit of time, the rate of disappearance of N₂O₄ is exactly half the rate of appearance of NO₂.
The expression that is true for the given reaction N₂O₄(g) ⇌2 NO₂(g) is B. -∆[N₂O₄]/∆t = ∆[NO₂]/∆t.
The rate of change of a reactant or product can be expressed as the ratio of the change in concentration of that species to the change in time (∆[N₂O₄]/∆t and ∆[NO₂]/∆t). According to the balanced chemical equation, 1 mol of N₂O₄ decomposes to produce 2 mol of NO₂. Therefore, the rate of change of N₂O₄ must be divided by 1 and the rate of change of NO₂ must be divided by 2 to obtain equivalent expressions for the reaction rate.
Thus, the correct expression is -∆[N₂O₄]/∆t = ∆[NO₂]/∆t.