10/14 Chemical Kinetics Free Online FlashCards

What does chemical kinetics study?

Chemical kinetics studies how fast reactions occur and how they proceed at the molecular level.

How are stoichiometric rates related?

For aA + bB → cC + dD, rate = −(1/a)Δ[A]/Δt = −(1/b)Δ[B]/Δt = (1/c)Δ[C]/Δt = (1/d)Δ[D]/Δt.

What do exponents in a rate law represent?

In rate = k[A]^m[B]^n, m and n are the orders in A and B; m + n is the overall order.

How does rate = k[A][B]² respond to doubled concentrations?

For rate = k[A][B]^2, doubling [A] doubles the rate, while doubling [B] quadruples it.

What are the general units of a rate constant?

For an overall order r, the rate constant has units [k] = M^(1−r) s^−1.

Which integrated law and plot identify first-order kinetics?

For a first-order reaction, ln[A]t = ln[A]0 − kt, and a plot of ln[A] versus t is linear with slope −k.

Which integrated law and plot identify second-order kinetics?

For a second-order reaction, 1/[A]t = 1/[A]0 + kt, and a plot of 1/[A] versus t is linear with slope +k.

What is the first-order half-life formula?

For a first-order reaction, t1/2 = 0.693/k. Therefore, its half-life does not depend on [A]0.

What is a reaction intermediate?

An intermediate is formed in one elementary step and consumed in a later step; it cancels when the steps are added.

What does molecularity describe?

Molecularity is the number of reactant particles involved in one elementary step: one is unimolecular, two bimolecular, and three termolecular.

What two tests must a proposed mechanism satisfy?

A proposed mechanism must add to the observed overall equation and produce the experimentally determined rate law.

What makes a collision successful?

A successful collision requires contact, sufficient energy to overcome Ea, and a suitable orientation for bonds to break and form.