Question

Write the rate law of the general equation given below and explain what is meant by the overall order and individual reactant order. aA + bB + cC → dD + eE A. Are the reaction order and stoichiometric coefficient related to each other? B. Does the reaction order have to always be a positive integer number? C. What is the rate constant? D. Does the rate constant depend on temperature? Be able to use stoichiometry to define a single unique average rate for the generic reaction: aA + bB + cC → dD + eE

Answer 1

Rate law: Rate = k x c_A^α x c_B ^β  xc_C ^γ

k is rate constant; α,β and γ are individual order with respect to A, B and C respectively. The overall order is (α + β + γ).

A) The numerical value of individual order should be obtained purely from experiment and not dependent on stoichiometric coefficient.

B)  The reaction order usually be a positive integer number but it may be zero, fraction and in some case negative.

C) The proportionality constant in rate equation is rate constant.

D) Rate constant increases with temperature by Arrhenius equation: k = A exp(-E/RT)

E) Av. rate = -(1/a)(d[A]/dt) = -(1/b)(d[B]/dt) = -(1/c)(d[C]/dt) = (1/d)(d[D]/dt) = (1/e)(d[E]/dt)