Final answer:
To express the reaction rate for 2 A(g) + B(g) → 3 C(g), you would use the change in concentration over time of reactants A (-1/2 Δ[A]/Δt) and B (-Δ[B]/Δt), or product C (+1/3 Δ[C]/Δt), factoring in the stoichiometry of the reaction.
Step-by-step explanation:
The question asks us to determine the expression for the rate of the reaction in terms of the change in concentration of each of the reactants and products for the reaction 2 A(g) + B(g) → 3 C(g). The rate of reaction is defined as the change in concentration of a reactant or product over time. For the given reaction, the rate can be expressed based on the consumption of reactants A and B, or the formation of product C.
The rate can be expressed in terms of the disappearance of A as - Δ[A]/Δt. However, because there are 2 moles of A reacting, the rate expression in terms of A is -1/2 Δ[A]/Δt. Similarly, for B, the rate is - Δ[B]/Δt. And for the production of C, the rate is +1/3 Δ[C]/Δt , reflecting the fact that for every one mole of B used or two moles of A used, three moles of C are produced.
These expressions show that the rate of reaction can be determined by the rate of decrease of reactants A or B or by the rate of increase of product C, keeping in mind the stoichiometry of the reaction. It's important to note that the rates based on the reactants will ordinarily be negative, as the concentration of reactants decreases over time, but chemists express rates as positive values.