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Question: For the reaction, \(2NO \to {N_2} + {O_2}\)the expression, \( - \dfrac{1}{2}\dfrac{{d\left[ {NO} \ri...

For the reaction, 2NO→N2+O22NO \to {N_2} + {O_2}the expression, −12d[NO]dt - \dfrac{1}{2}\dfrac{{d\left[ {NO} \right]}}{{dt}} represents:
A.The rate of formation of NONO
B.The average rate of the reaction
C.The instantaneous rate of reaction
D.All of the above

Explanation

Solution

To answer this question, you must recall the formula for the rate of a reaction. The substances that influence the rate of reaction are one or more of the reactants, but occasionally include products. Rate of reaction can also be defined as rate of consumption of reactant w.r.t. time.

Complete step by step answer:
The rate of change of concentration of a reactant is a negative quantity since the concentration decreases with time whereas, the rate of change of concentration of product is positive.
So the rate of the reaction is given as, Rate=−12Δ[NO]Δt=Δ[N2]Δt=Δ[O2]Δt{\text{Rate}} = - \dfrac{1}{2}\dfrac{{\Delta \left[ {NO} \right]}}{{\Delta t}} = \dfrac{{\Delta \left[ {{N_2}} \right]}}{{\Delta t}} = \dfrac{{\Delta \left[ {{O_2}} \right]}}{{\Delta t}}
−12d[NO]dt- \dfrac{1}{2}\dfrac{{d\left[ {NO} \right]}}{{dt}} is the differential which represents the change in concentration over a very small period of time, which we can say as instantaneous rate

Thus, the correct option is C.

Additional information:
While studying a chemical reaction, it is important for us to consider not only the chemical properties of the reactants, but also the conditions under which the reaction is taking place, the mechanism by which it is proceeding, the rate at which it is occurring, and the equilibrium towards which it is moving.
The law of mass action states that, at a constant temperature the rate of a chemical reaction at a constant temperature depends only on the concentrations of the substances influencing the rate. Catalysts, which do not appear in the balanced overall chemical equation, also influence reaction rate.

Note:
The rate law is an experimentally determined quantity and can be used to predict the relationship between the concentrations of reactants and the rate of the reaction. For elementary reactions, the rate equation can be derived from first principles using the collision theory. The rate equation of a reaction that has a multi-step mechanism cannot be calculated using the stoichiometric coefficients of the overall reaction.