14.5.1 Catalysts and Types of Catalysts

Question 1

Catalysts and Types of Catalysts

Answer 1

• Catalysis is the increasing of the reaction rate through the addition of a substance that is unchanged in the overall reaction.
• Homogeneous catalysts are in the same phase as the reactants, while heterogeneous catalysts are in a different phase than the reactants.
• Enzymes are biological catalysts.

Question 2

note

Answer 2

• Catalysis is the increasing of the reaction rate through the addition of a substance that is unchanged in the overall reaction (a catalyst).
• Catalysts act by lowering the activation energy (E a ) of the reaction. This is analogous to a tunnel dug through a mountain, allowing cars to pass through the mountain, rather than having to travel over the top.
• Homogeneous catalysts are in the same phase as the reactants. For example, iodide ion (I–) catalyzes the disproportionation of hydrogen peroxide (H 2 O 2 ). Both H 2 O 2 and iodide ion are in the aqueous phase.
• Heterogeneous catalysts are in a different phase than the reactants. For example, solid manganese(II) oxide (MnO 2 ) also catalyzes the disproportionation of aqueous hydrogen peroxide.
• Enzymes are nature’s catalysts. Examples of enzymes include catalase, amylase, proteases, alcohol dehydrogenase, and lactase.
• Catalase is present in blood and catalyzes the
  disproportionation of hydrogen peroxide.
• Amylase is present in saliva and breaks down starch into sugars.
• Lactase is used to digest lactose, a sugar in milk.
• Proteases aid in the digestion of proteins, and are used in drain cleaners.
• Alcohol dehydrogenase oxidizes alcohols, helping to clear them from the bloodstream.

Question 3

A catalytic converter is an example of which of the following?

Answer 3

Heterogeneous catalyst

Question 4

The Chinese word for catalyst is the same as the word for which of the following?

Answer 4

Matchmaker

Question 5

The starch-digesting enzyme found in saliva from the mouth is

Answer 5

Salivary amylase (ptyalin)

Question 6

A catalyst has which of the following properties?

Answer 6

A catalyst increases the rate of a reaction

Question 7

Which of the following reactions is catalyzed by platinum metal in a catalytic converter?

Answer 7

2NO2(g) + O2(g) → 2N2(g) + 3O2(g)

Question 8

Enzymes and catalysts do not make it possible to get a reaction to occur that would not eventually take place on its own. Catalysts act by:

Answer 8

lowering the activation energy (Ea ) of a reaction

Question 9

A catalytic converter contains inorganic catalysts that convert carbon monoxide (CO) and nitrogen monoxide (NO) to carbon dioxide (CO2 ) and nitrogen gas (N2 ). The correct classification for this type of catalyst is:

Answer 9

Heterogeneous catalyst

Question 10

Which of the following is not an enzyme?

Answer 10

Lactose

Question 11

Enzyme-containing powdered laundry detergent is an example of a:

Answer 11

Homogeneous catalyst

Question 12

The activation energy (Ea ) on a reaction diagram for an uncatalyzed reaction is generally ________ a catalyzed reaction.

Answer 12

greater than