AP Chem Unit 5 Kinetics Review

 A catalyst increases the rate of a chemical reaction by:

• Increasing the temperature of the reaction mixture

• Providing an alternative reaction pathway with a higher activation energy

• Being consumed in the reaction

• Lowering the activation energy of the reaction

Answer explanation

It offers an alternative pathway with a lower activation energy - Catalysts typically lower activation energy. Means less energy is needed to react

Tags

NGSS.HS-PS1-4

The rate of a certain reaction is given by the expression Rate = k[A][B]^2. If the concentration of B is doubled, the rate of the reaction will:

• Remain the same

• Double

• Quadruple

• Octuple

Tags

NGSS.HS-PS1-5

A reaction has a rate constant (k) of 2.5 x 10^-3 s^-1 at 25°C. If the activation energy is 75 kJ/mol, what will be the rate constant at 35°C?

• 2.5 x 10^-3 s^-1

• Greater than 2.5 x 10^-3 s^-1

• Less than 2.5 x 10^-3 s^-1

• Cannot be determined without additional information

Answer explanation

It will increase - higher temperatures generally increase k, following the Arrhenius equation

Tags

NGSS.HS-PS1-5

For the reaction A → B, the rate decreases over time because:

• The concentration of A decreases

• The concentration of B increases

• The activation energy increases

• The temperature of the system decreases

Answer explanation

The concentration of A decreases - As reactants are consumed, reaction rates often decrease.

Tags

NGSS.HS-PS1-5

The half-life of a first-order reaction is independent of:

• Temperature

• Initial concentration of reactant

• Activation energy

• Presence of a catalyst

Answer explanation

Initial concentration of reactant - For first-order reactions, half-life is constant.

The mechanism of a reaction is determined by:

• The balanced chemical equation

• The activation energy

• The rate law

• The change in enthalpy

Answer explanation

The rate law - Mechanisms explain the steps that constitute the overall rate law.

For a certain reaction, the activation energy is 56 kJ/mol. If the temperature is increased from 300K to 310K, what will happen to the rate constant (k)?

• It will increase

• It will decrease

• It will remain constant

• Cannot be determined without additional information

Answer explanation

It will increase - Higher temperatures generally increase k, following the Arrhenius equation.

Tags

NGSS.HS-PS1-5

In a reaction, the rate is directly proportional to the square of the concentration of reactant A. This indicates that:

• The reaction is zero order in A

• The reaction is first order in A

• The reaction is second order in A

• The reaction order cannot be determined

Answer explanation

The reaction is second order in A - Rate is proportional to the square of [A].

Tags

NGSS.HS-PS1-5

A reaction has a rate law of Rate = k[A]^2. If the concentration of A is quadrupled, the rate of the reaction will:

• Double

• Quadruple

• Increase sixteen times

• Remain the same

Answer explanation

Increase sixteen times - Quadrupling A in a second-order reaction increases rate 16 times.

Tags

NGSS.HS-PS1-5

The rate constant of a reaction doubles for every 10°C rise in temperature. This behavior is indicative of:

• A low activation energy

• A high activation energy

• A catalyst present in the reaction

• A reversible reaction

Answer explanation

A high activation energy - Large temperature effect indicates high activation energy.

Tags

NGSS.HS-PS1-5