Question

show the enthalpy profile of either an exothermic or endothermic reaction and show how the presence of a catalyst changes the reaction profile. Make sure that your chosen enthalpy profile includes “activation energy”

Answer 1

Explanations:

Exothermic reactions are reactions that release heat to the surroundings during the chemical reactions. The enthalpy change for an exothermic reaction is negative because the the energy the product is less than that of the reactant.

For exothermic reactions:

`\triangle H=H_p-H_r<0`

The enthalpy profile shows how the energy changes during a reaction. The enthalpy profile for an exothermic reaction is as shown below:

From the diagram, the definition of the symbols are

`\begin{gathered} \triangle H\text{ is the enthalpy change} \\ E_A\text{ is the activation energy} \end{gathered}`

The presence of any catalyst in a chemical reaction speeds up the rate of the chemical reaction by lowering the activation energy in the reaction profile.