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

First order

Answer

Second order

Answer

Sixth order

Question 2

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

Accepted Answer

Increase k while leaving Ea unchanged

Answer

Decrease k while increasing Ea

Answer

Decrease both k and Ea

Answer

Increase both k and Ea

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

t₁/₂ = k/ln(2)

Answer

t₁/₂ = 1/(2k[A]₀)

Answer

t₁/₂ = 2/k[A]₀

Question 4

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

Accepted Answer

Method of initial rates

Answer

Van't Hoff equation analysis

Answer

Arrhenius plot analysis

Answer

Integrated rate law fitting only

Question 5

A homogeneous catalyst increases reaction rate primarily by:

Accepted Answer

Providing an alternative pathway with lower activation energy

Answer

Raising the temperature of the reaction mixture

Answer

Shifting the equilibrium position toward products

Answer

Increasing the concentrations of reactants

Question 6

For a zero-order reaction, plotting [A] versus time yields:

Accepted Answer

A straight line with slope = -k

Answer

An exponential decay curve

Answer

A straight line with slope = +k

Answer

A curve with increasing slope

Question 7

In the Arrhenius equation, the pre-exponential factor A (frequency factor) physically represents:

Accepted Answer

The collision frequency weighted by the steric factor for correct orientation

Answer

The activation energy normalized by the gas constant

Answer

The maximum reaction rate at infinitely high temperature

Answer

The equilibrium constant at standard conditions