Chapter 21, Problem 21.84QP

Interpretation Introduction

Interpretation:

Rate law (a), simplified rate law (b), half-life when the initial concentration of NO was 10 ppm (c) should be determined for the given reaction.

Concept Introduction:

• According with rate law the rate of a chemical reaction is directly proportional to the initial concentration of reactants.

That is for a general reaction, $\text{A}\text{+}\text{B}\to \text{product}$,

$\text{Rate}\text{=}\text{k}\text{[A][B]}$ k is the rate constant.

• Half-life ( ${\text{t}}_{\frac{\text{1}}{\text{2}}}$) is the time required for a quantity to reduce to half its initial value.

  Half-life for a second order reaction ${\text{t}}_{\frac{\text{1}}{\text{2}}}\text{=}\frac{\text{1}}{\text{k}{\left[\text{A}\right]}_{\text{0}}}$   k is the rate constant. ${\left[\text{A}\right]}_{\text{0}}$ is the initial concentration of the reactant

• The units of rate constant will changes with order of the reaction. For a first order reaction the unit of rate constant is ${\text{s}}^{\text{-1}}$.
• Order of a reaction is the sum of powers of the concentration terms in the rate equation.

  That is for general reaction $\text{aA}\text{+}\text{bB}\to \text{product}$,

$\text{Rate}\text{=}\text{k}{\text{[A]}}^{\text{a}}{\text{[B]}}^{\text{b}}$ k is the rate constant.

Order of the reaction = a + b

• In a second-order reaction its rate proportional to the concentration of two reactant.
• Pseudo second order reaction is one type of reaction which is appeared as a higher order reaction but actually it follows second order kinetics.

To determine: the rate law for the given reaction