Catalysts Assignment and Quiz
Which of the following statements describes how enzymes differ from ordinary chemical catalysts?
Enzymes catalyze select chemical reactions.
Consider the energy diagram below. mc022-1.jpg Which statement best describes the diagram?
The catalyzed reaction passes through C.
A reaction is shown below. Reaction : mc023-1.jpg What can be concluded about this reaction?
A heterogeneous catalyst is being used in the reaction.
Why are enzymes required for living things to function?
Reactions take place too slowly at body temperature and must be speeded up.
Which characteristic of enzymes allows it to be highly specific in the reactions they catalyze?
its structure
Which reaction is an example of heterogeneous catalysis?
Ethene gas reacts with hydrogen gas by using a nickel catalyst.
Which statement describes a heterogeneous catalyst?
It is in a different phase than the reactants.
Sulfuric acid was once produced through the reaction of sulfur trioxide with water. Sulfur trioxide can form through the reaction of sulfur dioxide and oxygen gas. When nitrogen monoxide gas is added to the system, the reaction speeds up significantly because it proceeds through the following steps: equations Identify the catalyst in this reaction, explain how you know it is the catalyst, and describe how it increases the rate of the reaction.
NO is the catalyst. NO is the catalyst because it increases the rate of the reaction but is not consumed during the reaction. NO increases the rate of the reaction by lowering the activation energy. The reaction of NO with O2 provides an alternative reaction pathway with a lower activation energy.
The second reaction in the formation of sulfuric acid occurs slowly. mc011-1.jpg NO2 is added to the reaction to speed it up. In which form would this substance be a homogeneous catalyst for this reaction?
NO2(g)
Which statement describes a catalyst?
Catalysts provide a lower energy pathway for the reaction.
What overall effect does adding a catalyst have on a chemical reaction?
It lowers the activation energy that is needed.
The hydrogenation of unsaturated hydrocarbons is an important industrial process. Precious metals, such as platinum and palladium, can greatly increase the rate of this reaction. During this process, the gaseous reactants are pumped across a layer of metal powder. An example of this process is shown below. Hydrogenation on catalyst Describe how the metal probably increases the reaction rate, identify whether this is an example of homogeneous or heterogeneous catalysis, and explain how you know.
The metal probably increases reaction rate by either holding reactant molecules in the correct orientation to react or by weakening or breaking bonds in reactant molecules to make them more reactive. This is an example of heterogeneous catalysis. It is heterogeneous catalysis because the catalyst is a solid and the reactants are gases. In heterogeneous catalysis, the catalyst is in a different phase than the reactants.
Urea is a product of digestion of proteins and other foods that contain nitrogen. It can react with water and acid to form ammonium ions and bicarbonate ions according to the equation below: reaction energy diagram The enzyme urease catalyzes this reaction. If urease is added to a solution that contains ammonia and other nitrogen-containing compounds (but no urea), will the urease catalyze any reactions? Explain your answer.
Urea is a product of digestion of proteins and other foods that contain nitrogen. It can react with water and acid to form ammonium ions and bicarbonate ions according to the equation below: reaction energy diagram The enzyme urease catalyzes this reaction. If urease is added to a solution that contains ammonia and other nitrogen-containing compounds (but no urea), will the urease catalyze any reactions? Explain your answer.
