CP4 Finding the Activation Energy of a Reaction

• The Arrhenius equation is represented as $k =$$Ae^{ - E_{a} / RT}$


  True
• What type of graph is created to determine activation energy?

  \ln k vs. 1/T
• Match the feature with its effect on activation energy or enthalpy change:

  Activation Energy ↔️ Minimum energy to start a reaction

  Enthalpy Change ↔️ Difference in energy between reactants and products

  Symbol for Activation Energy ↔️ \( E_a \)

  Symbol for Enthalpy Change ↔️ \( \Delta H \)
• How does a higher activation energy affect the reaction rate?

  Slows it down
• Catalysts lower activation energy by providing an alternative pathway
• A catalyst provides an alternative pathway with lower activation energy.


  True
• What happens to activation energy when temperature increases?

  It decreases
• Match the term in the Arrhenius equation with its definition:

  Rate constant (k) ↔️ Measure of reaction speed

  Pre-exponential factor (A) ↔️ Frequency of effective collisions

  Activation energy (Ea) ↔️ Minimum energy for reaction

  Ideal gas constant (R) ↔️ Universal constant for gases
• What is the unit of activation energy in the Arrhenius equation?

  J/mol
• What does $k$ represent in the Arrhenius equation?


  Rate constant
• The ideal gas constant $R$ is 8.314 J/(mol·K).


  True
• Steps for collecting rate constants at different temperatures:

  1️⃣ Prepare identical reaction setups

  2️⃣ Perform the reaction at multiple temperatures

  3️⃣ Measure the rate constant at each temperature

  4️⃣ Record all temperature and rate constant values
• Activation energy affects reaction spontaneity.

  False
• What visually represents the energy changes throughout a reaction?

  Energy profile
• Lower activation energy leads to faster reaction rates.


  True
• Activation energy is distinct from enthalpy change.
• What does the Arrhenius equation describe?

  Rate constant relationship
• What is activation energy defined as?

  Minimum energy for reaction
• The linearized form of the Arrhenius equation is $\ln k =$$\ln A - \frac{E_{a}}{R} \left(\frac{1}{T}\right)$ where the activation energy is divided by R
• The activation energy can be determined from the slope of the $\ln k$ vs. $\frac{1}{T}$ graph.


  True
• The reaction mechanism outlines the steps involved, while the energy profile visually represents the energy changes throughout the reaction
• Increasing temperature decreases activation energy.


  True
• What happens to the reaction rate when activation energy is lowered?

  It increases
• Activation energy affects the reaction rate, while enthalpy change affects the reaction spontaneity
• The Arrhenius equation relates the rate constant to activation energy and temperature.


  True
• The ideal gas constant (R) has a value of 8.314
• The Arrhenius equation is represented as k = Ae^{ - E_{a} / RT}
• What does E_{a}</latex> represent in the Arrhenius equation?

  Activation energy
• Match the term with its unit:

  Rate constant ↔️ s^-1

  Activation energy ↔️ J/mol

  Pre-exponential factor ↔️ Same as rate constant
• Activation energy is the minimum energy needed to form products
• Match the feature with the correct concept:

  Minimum energy to start a reaction ↔️ Activation energy

  Energy difference between reactants and products ↔️ Enthalpy change
• Higher activation energy results in a slower reaction rate.
• How does temperature affect activation energy?

  Decreases it
• The rate constant increases as the activation energy decreases or the temperature increases.


  True
• The Arrhenius equation is given by: $k =$$Ae^{ - E_{a} / RT}$
• The pre-exponential factor $A$ has the same units as the rate
• What is the activation energy in the example calculation?

  $50,000 \, \text{J / mol}$
• Higher temperatures provide more energy to overcome the activation energy barrier.

  True
• What unit is the absolute temperature $T$ measured in for the Arrhenius equation?


  Kelvin
• The Arrhenius equation shows that the rate constant increases as the temperature increases