Reversible reactions and equilibrium

A negative ΔH value indicates that the forward reaction is exothermic, meaning it releases heat to the surroundings.

Increasing the temperature decreases the yield of the products in an exothermic reaction. According to Le Chatelier's principle, the equilibrium will shift to favour the endothermic (reverse) reaction to counteract the increase in temperature.

Adding a reactant increases the yield of the products. The equilibrium will shift to the right to consume the added reactant (CO) and re-establish equilibrium.

Increasing the pressure shifts the equilibrium towards the side with fewer moles of gas. For

A catalyst has no effect on the position of equilibrium. It increases the rate of both the forward and reverse reactions equally, so the equilibrium is reached faster, but the final concentrations of reactants and products remain the same.

Increasing the concentration of a solution increases the rate of reaction. According to collision theory, a higher concentration means more particles per unit volume, leading to a higher frequency of collisions.

Increasing the surface area of a solid increases the rate of reaction. A larger surface area provides more area for the reactants to collide, leading to a higher frequency of successful collisions.

Increasing temperature increases the rate of reaction. Higher temperature means particles have more kinetic energy, leading to more frequent and more energetic collisions. More collisions exceed the activation energy, Ea, resulting in more successful reactions.

Adding a catalyst increases the rate of reaction by decreasing the activation energy (Ea). This means that a greater proportion of collisions have enough energy to overcome the energy barrier and react. The catalyst itself is unchanged.