ACS CP Thermodynamics & Chemical Kinetics 2

Question 1

For a reaction with rate law r = k[A]²[B], what is the overall reaction order?

Accepted Answer

Third order

Answer

The overall reaction order is the sum of all exponents in the rate law: 2 + 1 = 3 (third order overall).

Question 2

The Arrhenius equation k = A·e^(-Ea/RT) predicts that increasing temperature will:

Accepted Answer

Increase k while leaving Ea unchanged

Answer

Increasing T raises k via the exponential factor e^(-Ea/RT), while activation energy Ea is an intrinsic molecular property unaffected by T.

Question 3

For a first-order reaction A → products with rate constant k, the half-life (t₁/₂) is given by:

Accepted Answer

t₁/₂ = ln(2)/k

Answer

For a first-order reaction, t₁/₂ = ln(2)/k = 0.693/k, which is independent of initial concentration.

Question 4

Which experimental technique determines the order of a reaction with respect to individual reactants?

Accepted Answer

Method of initial rates

Answer

The method of initial rates involves varying one reactant concentration while holding others constant, then measuring the initial rate to determine individual orders.

Question 5

A homogeneous catalyst increases reaction rate primarily by:

Accepted Answer

Providing an alternative pathway with lower activation energy

Answer

A catalyst provides an alternative mechanism with a lower activation energy barrier, increasing k without being consumed in the overall reaction.

(ACS CP) American Chemical Society (ACS) Certified Professional Practice Test

(ACS CP) American Chemical Society (ACS) Certified Professional Practice Test

ACS CP Thermodynamics & Chemical Kinetics 2