Draw an energy versus reaction progress diagram (similar to...

Draw an energy versus reaction progress diagram (similar to the one in Question 64 ) for each of the reactions whose activation energy and enthalpy change are given below. (a) $\Delta H^{\circ}=-145 \mathrm{~kJ} \mathrm{~mol}^{-1} ; E_{\mathrm{a}}=75 \mathrm{~kJ} \mathrm{~mol}^{-1}$ (b) $\Delta H^{\circ}=-70 \mathrm{~kJ} \mathrm{~mol}^{-1} ; E_{\mathrm{a}}=65 \mathrm{~kJ} \mathrm{~mol}^{-1}$ (c) $\Delta H^{\circ}=70 \mathrm{~kJ} \mathrm{~mol}^{-1} ; E_{\mathrm{a}}=85 \mathrm{~kJ} \mathrm{~mol}^{-1}$

Draw an energy versus reaction progress diagram (similar to the one in Question 64 ) for each of the reactions whose activation energy and enthalpy change are given below.
(a) $\Delta H^{\circ}=-145 \mathrm{~kJ} \mathrm{~mol}^{-1} ; E_{\mathrm{a}}=75 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(b) $\Delta H^{\circ}=-70 \mathrm{~kJ} \mathrm{~mol}^{-1} ; E_{\mathrm{a}}=65 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(c) $\Delta H^{\circ}=70 \mathrm{~kJ} \mathrm{~mol}^{-1} ; E_{\mathrm{a}}=85 \mathrm{~kJ} \mathrm{~mol}^{-1}$

Key Concepts

Exothermic and Endothermic Reactions

These terms describe the energy flow during chemical reactions. Exothermic reactions emit energy, resulting in products that are at a lower energy level compared to the reactants, whereas endothermic reactions absorb energy, resulting in products that have a higher energy level than the reactants. This distinction is visually represented in the energy diagrams where the relative positions of the reactants and products indicate whether the reaction releases or requires energy.

Reaction Coordinate Diagram

This diagram is a graphical representation that illustrates the energy changes that occur as reactants convert to products during a chemical reaction. It typically plots energy on the vertical axis against the progress of the reaction on the horizontal axis, highlighting key stages such as the starting energy level of the reactants, the peak representing the transition state (where the activation energy is overcome), and the final energy level of the products.

Activation Energy

Activation energy is the minimum energy required for reactants to overcome the energy barrier and form the transition state, initiating the reaction. It is represented by the height of the peak in an energy versus reaction progress or reaction coordinate diagram and determines the rate at which the reaction proceeds.

Reaction Enthalpy

Reaction enthalpy, denoted as ?H, is the overall heat change during a chemical reaction. It is calculated as the difference between the energy levels of the products and the reactants. A negative ?H indicates that the reaction is exothermic, releasing energy, while a positive ?H means the reaction is endothermic, absorbing energy.

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