Speeding Up a Chemical Reaction

CHAPTER 16 Kinetics Rates and Mechanisms of Chemical Reactions 

Consider a general uncatalyzed reaction that proceeds by a one-step mechanism involving a bimolecular collision  

In the catalyzed reaction, a reactant molecule interacts with the catalyst, so the mechanism might involve a two-step pathway  

Note that the catalyst is not consumed, as its definition requires. Rather, it is used and then regenerated, and the activation energies of both steps are lower than the activation energy of the uncatalyzed pathway. 

There are two general categories of catalyst—homogeneous catalysts and heterogeneous catalysts—based on whether the catalyst is in the same phase as the reactant and product. 

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Catalyst A substance used to speed up a chemical reaction, including the transformation of certain pollutants present in a combustion process. 

C15-0121. Use molecular arguments to explain why each of the following factors speeds up a chemical reaction ... 

This is the same reaction that occurs in Venus atmosphere. Here on Earth, however, this reaction can be slow. To speed it up, the reaction is catalyzed. Remember, a catalyst is a chemical that speeds up a chemical reaction without taking part in the reaction itself. When chemicals are mixed together, they will only react with one another if their particles (atoms and molecules) collide. If the reactants never come into contact, a chemical reaction will not take place. 

A catalyst is a substance that speeds up a chemical reaction without undergoing a permanent change in its own composition. Catalysts are often but not always noted above or below the arrow in the chemical equation. Since a small quantity of catalyst is sufficient to cause a large quantity of reaction, the amount of catalyst need not be specified it is not balanced like the reactants and products. In this manner, the equation for a common laboratory preparation of oxygen is written... 

An enzyme is a protein molecule that speeds up a chemical reaction. 

Catalyst Any matter that is used to change or speed up a chemical reaction without being changed itself or destroyed in the reaction. 

Catalyst Cell A chemical that initiates or speeds up a chemical reaction. A single small cavity surrounded partially or completely by walls. 

Catalysts are substances that speed up a chemical reaction without themselves being consumed in the reaction. The most sophisticated catalysts of all are those found in living systems. They bring about reactions that could not be performed at all, or only with great difficulty, outside a living organism. These catalysts are called enzymes. In addition to speeding up reactions by as much as 10- to a 100 million-fold, enzymes are extremely selective in the reactions they promote. 

Enzymes are usually large long-chain protein molecules that act as a catalyst for chemical reactions in the body. A catalyst is a material that speeds up a chemical reaction but is itself unchanged at the end of the reaction. Very small amounts of... 

A catalyst is a substance that can speed up a chemical reaction and can be recovered chemically unchanged at the end of the reaction. 

Cerium is also used in catalytic systems. A catalyst is a substance used to speed up a chemical reaction. The catalyst does not undergo any change itself during the reaction. Compounds of cerium are used in the refining of petroleum. They help break down compounds found in petroleum into simpler forms that work better as fuels. 

Few holmium compounds have any important commercial uses. The one exception is holmium oxide (H02O3), used to add a yellowish color to glass, in the manufacture of refractory materials, and as a catalyst for some chemical reactions. A refractory material is a material that can withstand very high temperatures and reflect heat back away from itself A catalyst is a substance used to speed up a chemical reaction without undergoing any change itself In 2007, the price of holmium oxide was approximately 750 per kilogram. 

Palladium has two primary uses as a catalyst and in making jewelry and specialized alloys. A catalyst is a substance used to speed up a chemical reaction without undergoing any change itself. Palladium catalysts are used in breaking down petroleum to make high quality gasoline and other products. It is also used in the production of some essential chemicals, such as sulfuric acid (H2SO4), which is used in paper and fabric production. The catalytic converters used in automobiles today may also contain a palladium catalyst. A catalytic converter is a device added to a car s exhaust system. It helps the fuel used in the car burn more efficiently. 

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