7. (a) What is a catalyst? (b) Explain how the type of bonding in the reactants influences the rate of a chemical reaction in aqueous solution - Leaving Cert Chemistry - Question 7 - 2015

In aqueous solutions, ionic compounds react almost instantaneously as they dissociate into ions, allowing for immediate interaction with other reactants. In contrast, covalent compounds react more slowly because the bonds must be broken before new bonds can form.

The rate of a reaction can be reduced by lowering the concentration of reactants, which decreases the frequency of collisions between reacting particles. Additionally, cooling the reaction mixture can slow down the movement of particles, further reducing the rate of reaction.

One observation during the experiment may be that the solution changes color or emits a gas. Two major products of the oxidation of methanol are formaldehyde (HCHO) and hydrogen (H2).

The term used to describe the attachment of molecules to a solid surface is 'adsorption'.

The interaction of methanol with the platinum catalyst involves adsorption onto the catalyst's surface, which provides active sites for the reaction. This can lower the activation energy and increase the likelihood of effective collisions, thereby speeding up the rate of reaction.

Activation energy (E_a) is the minimum energy required for a chemical reaction to occur. It represents the energy barrier that reactants must overcome to be converted into products.

The reaction profile diagram should depict the progress of the reaction on the x-axis and the energy on the y-axis. The graph will show the reactants starting at a certain energy level, rising to a peak representing the activation energy (E_a), and then dropping down to a lower energy level for the products, indicating that it is an exothermic reaction. The difference in height between the reactants and products is the heat of reaction (∆H). The diagram should be clearly labeled.