Rates of Reaction SAQ2

A catalyst is a substance that alters the rate of a chemical reaction, but is chemically unchanged at the end of the reaction.

Heterogeneous catalysis occurs when the catalyst is in a different physical phase to the reactants, whereas homogeneous catalysis occurs when the catalyst is in the same physical phase as the reactants.

The minimum energy required is the activation energy (EACT), and a collision that meets this energy requirement is called an effective collision.

<p>The term for this process is autocatalysis.</p> Signup and view all the answers

<p>The instantaneous rate of a reaction is the rate at a particular point in time during the reaction, whereas the average rate of a reaction is the rate over a longer period of time.</p> Signup and view all the answers

<p>The theory is called the intermediate formation theory.</p> Signup and view all the answers

<p>An unstable intermediate is formed between a reactant and a catalyst, and it quickly breaks down to form the product, with the catalyst being regenerated in the process.</p> Signup and view all the answers

<p>Adsorption is the accumulation of one substance at the surface of another, whereas absorption is the penetration of one substance into another. Surface adsorption theory is a type of heterogeneous catalysis where reactants adsorb onto the surface of a solid catalyst.</p> Signup and view all the answers

<p>Active sites are areas on the catalyst surface where the reaction between reactants takes place. Certain particles, such as lead and arsenic, can block these active sites, acting as catalytic poisons.</p> Signup and view all the answers

<p>The more finely divided or porous the catalyst, the greater the reaction rate, due to the increased availability of catalytic sites.</p> Signup and view all the answers

<p>If ΔH is negative, the reaction is exothermic, meaning heat is lost. If ΔH is positive, the reaction is endothermic, meaning heat is absorbed. This can be determined by measuring the heat change during the reaction.</p> Signup and view all the answers

<p>An increase in temperature of 10K would result in a small (50%) increase in the number of collisions, but no change in the activation energy.</p> Signup and view all the answers