Question

consider a hypothetical chemical reaction: a + b → c + d (in this equation a, b, c and d stand for some unknown chemical formulas.) here is an energy diagram for the reaction: energy diagram description with energy in kj/mol on y - axis and reaction coordinate on x - axis, showing a + b at lower energy and c + d at higher energy use the energy diagram to answer these questions. what is the heat of reaction? kj/mol is the reaction exothermic or endothermic? exothermic endothermic neither can you determine the activation energy? yes, its kj/mol no. can you determine the activation energy of the reverse reaction? c + d → a + b yes, its kj/mol no.

Explanation:

Step1: Calculate heat of reaction

Heat of reaction ($\Delta H$) is energy of products - energy of reactants. From the graph, energy of reactants ($A + B$) is 150 kJ/mol and energy of products ($C + D$) is 200 kJ/mol. So, $\Delta H=200 - 150$.

Step2: Determine reaction type

Since $\Delta H> 0$ (products have higher energy than reactants), the reaction is endothermic.

Step3: Find activation energy

Activation energy ($E_a$) is the energy difference between the transition - state and the reactants. The transition - state energy is 400 kJ/mol and reactant energy is 150 kJ/mol. So, $E_a = 400-150$.

Step4: Find reverse - reaction activation energy

For the reverse reaction $C + D
ightarrow A + B$, the activation energy is the energy difference between the transition - state and the products. The transition - state energy is 400 kJ/mol and product energy (for reverse reaction, $C + D$ are reactants) is 200 kJ/mol. So, $E_{a_{reverse}}=400 - 200$.

Answer:

What is the heat of reaction? 50 kJ/mol
Is the reaction exothermic or endothermic? Endothermic
Can you determine the activation energy? Yes, it's 250 kJ/mol
Can you determine the activation energy of the reverse reaction? Yes, it's 200 kJ/mol