Questions: A reaction profile (not to scale) for the reaction 2 HI -> H2 + I2 is shown below: Reaction Coordinate What is the value of the activation energy for this reaction? kJ Is this reaction exothermic or endothermic? What is the value of ΔE for the reaction? kJ

Transcript text: A reaction profile (not to scale) for the reaction \[ 2 \mathrm{HI} \longrightarrow \mathrm{H}_{2}+\mathrm{I}_{2} \] is shown below: Reaction Coordinate What is the value of the activation energy for this reaction? $\square$ kJ Is this reaction exothermic or endothermic? $\square$ What is the value of $\Delta E$ for the reaction? $\square$ kJ

Solution

Solution Steps

Step 1: Determine the Activation Energy

The activation energy (Ea) is the energy difference between the reactants and the peak of the energy profile. From the graph, this value is given as 184 kJ.

Step 2: Determine if the Reaction is Exothermic or Endothermic

To determine if the reaction is exothermic or endothermic, compare the energy of the reactants and products. The products (H2 + I2) have a higher energy (13 kJ) compared to the reactants (0 kJ). Since the products have higher energy, the reaction absorbs energy, making it endothermic.

Step 3: Calculate the Change in Energy (ΔE)

The change in energy (ΔE) for the reaction is the difference in energy between the products and the reactants. From the graph, the energy of the products is 13 kJ and the energy of the reactants is 0 kJ. Therefore, ΔE = 13 kJ - 0 kJ = 13 kJ.