chapter chemical kinetic ...... what us the difference between overall reaction and order of a reaction
Answers
order of reaction:
The order of reaction can be defined as the power dependence of rate on the concentration of all reactants. For example, the rate of a first-order reaction is dependent solely on the concentration of one species in the reaction. Some characteristics of the reaction order for a chemical reaction are listed below.
Reaction order represents the number of species whose concentration directly affects the rate of reaction.
It can be obtained by adding all the exponents of the concentration terms in the rate expression.
The order of reaction does not depend on the stoichiometric coefficients corresponding to each species in the balanced reaction.
The reaction order of a chemical reaction is always defined with the help of reactant concentrations and not with product concentrations.
The value of the order of reaction can be in the form of an integer or a fraction. It can even have a value of zero.
In order to determine the reaction order, the power-law form of the rate equation is generally used. The expression of this form of the rate law is given by r = k[A]x[B]y.
A hypothetical reaction A2+B2?2AB follows the mechanism as given below:A2?A+A (fast) A+B2?AB+B (slow) A+B?AB (fast) The order of the overall reaction is (1) 2 (2) 1 (3) 1.5 (4) 0
Since (A) is the intermediate reactive substance whose concentration is determined from the equilibrium step.
Let us consider the slow step of the reaction
A + B2 → AB + B (slow)
r = k[A][B2]…………….(1)
From the equilibrium step
A2⇌ A + A (fast)
keq = [A]2/[A2]
∴ [A] = keq[A2]1/2
Substitute the value of [A] in equation (1)
r = k[ keq[A2]1/2][B2]
r = k. keq1/2.[A2]1/2. B2
Thus, the order of the reaction is
⇒ 1/2 +1
⇒ 3/2
⇒ 1.5
In the expression described above, ‘r’ refers to the rate of reaction, ‘k’ is the rate constant of the reaction, [A] and [B] are the concentrations of the reactants. The exponents of the reactant concentrations x and y are referred to as partial orders of the reaction. Therefore, the sum of all the partial orders of the reaction yields the overall order of the reaction.
answer : The attachment above are the answers
