Multiple choice questions

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Chapter 27: Catalysis and some industrial processes

For some of these questions, you need data from the appendices of Inorganic Chemistry, third edition by C.E. Housecroft and A.G. Sharpe. On opening the book cover you will find a periodic table and a list of elements and atomic masses. Physical constants are listed on the back inside cover of the book.

Multiple choice questions by Catherine E. Housecroft.

This activity contains 20 questions.

Which statement about a catalyst is incorrect?

	The presence of a catalyst speeds up a reaction
	The presence of a catalyst changes the rate of a reaction
	In some reactions, one of the products acts as a catalyst for the forward reaction
	During use, a catalyst may be poisoned

Which of the following criteria is least important for a homogeneous, organometallic catalyst?

	The metal centre must normally be able to accommodate both a 16 or 18 valence electron count
	The metal centre must be able to tolerate more than one ligand geometry
	The metal centre must be able to undergo oxidation and reduction reactions
	The catalyst must be contain a third row d-block metal

Match the compound formula to its application as a catalyst or catalyst precursor in the stated process. Which pair is incorrect?

	cis-[Rh(CO)₂I₂]^–; Monsanto acetic acid synthesis
	RhCl(PPh₃)₃; alkene hydrogenation
	HRh(PPh₃)₃; asymmetric hydrogenation
	HCo(CO)₄; hydroformylation of alkenes

Hydroformylation of alkenes may lead to alcohol and aldehyde products. Which statement is correct?

	The stereoselectivity of the reaction gives the aldehyde:alcohol ratio
	The chemoselectivity of the reaction gives the n:i aldehyde ratio
	The regioselectivity of the reaction gives the aldehyde:alcohol ratio
	The regioselectivity of the reaction gives the n:i aldehyde ratio

In the Tennessee–Eastman acetic anhydride process, the catalyst is cis-[Rh(CO)₂I₂]^–. Which sequence of steps best describes the primary catalytic cycle?

	Oxidative addition of MeI and loss of CO; Me migration; addition of 2 CO; elimination of MeC(O)I
	Oxidative addition of MeI; Me migration; CO addition; elimination of MeC(O)I
	Loss of CO; oxidative addition of MeI; Me migration; addition of 2 CO; elimination of MeC(O)I
	Oxidative addition of MeI; CO migration to the Me group; CO addition; elimination of MeC(O)I

Which statement is incorrect about chemisorption of CO on a metal (M) surface?

	CO molecules are activated
	IR spectroscopy can be used to study the system
	M–C bonds are formed
	The CO molecules must be terminally bound

Which statement is incorrect about the industrial Haber process for NH₃ production?

	The catalyst used commercially is α-Fe; catalyst promoters are added
	Chemisorption of N₂ and H₂ activates the molecules, weakening and cleaving their bonds
	A high temperature is needed because the forward reaction is endothermic
	Both a high temperature and pressure are required

The following statements are about catalytic converters. Which one is incorrect?

	Permissible emission gases are CO₂, N₂ and H₂O
	The precious metals Rh, Pt and Pd are used in 3-way converters
	Ce₂O₃/CeO₂ is an "O₂ storage" additive
	Rh catalyses the oxidation of NO

In the hydrogenation of alkenes using Wilkinson's catalyst, the active catalyst is RhCl(PPh₃)₂ (or RhCl(PPh₃)₂(solvent)). The first step in the catalytic cycle is:

	alkene coordination
	oxidative addition of H₂
	loss of PPh₃
	loss of Cl^–

A key feature of the Fischer-Tropsch process is:

	hydrocarbon formation
	alkene hydrogenation
	alkene polymerization
	hydroformylation

Which step, taken from a catalytic cycle, is an example of reductive elimination?

	Loss of RCH₂CH₃ from Rh(H)₂(CO)(PPh₃)₂(CH₂CH₂R)
	Conversion of Rh(CO)₂(PPh₃)₂(CH₂CH₂R) to Rh(CO)(PPh₃)₂(COCH₂CH₂R)
	Reaction of Rh(CO)(PPh₃)₂(CH₂CH₂R) with H₂
	Loss of RCH=CHR from PdX(PPh₃)₂(CHRCH₂R) and formation of Pd(H)X(PPh₃)₂

Which of the following compounds is a 16-electron species and is an active catalyst?

	HCo(CO)₃
	HRh(CO)(PPh₃)₃
	[Rh(CO)₂I₄]^–
	Pd(PPh₃)₄

Typical Grubbs' catalysts contain:

	Ru; a carbene ligand
	Rh; a carbene ligand
	Ru; an alkene ligand
	Rh; an alkene ligand

Adsorption of a species X onto a surface with concomitant surface–X bond formation is called:

	chemisorption
	catalysis
	desorption
	physisorption

Which statement is incorrect about zeolites?

	No zeolites occur naturally
	Zeolites are aluminosilicates
	Each zeolite contains channels of a specific size
	A zeolite functions as an acid catalyst, e.g. in the alkylation of aromatic compounds

A Schrock-type catalyst for alkyne metathesis may contain:

	high oxidation state tungsten and a W=CR₂ unit
	low oxidation state tungsten and a W=CR₂ unit
	low oxidation state tungsten and a W≡CR unit
	high oxidation state tungsten and a W≡CR unit

One of the following ligands is chiral. Which is it?

	Me₂PCH₂CH₂PPh₂
	Me₂PCH₂CH₂PMe₂
	Me₂PCHMeCH₂PMe₂
	Me₂PCH₂CH₂AsMe₂

Ziegler-Natta catalysis is associated with:

	alkene hydrogenation
	alkene polymerization
	hydroformylation of alkenes
	alkyne metathesis

The oxidation of SO₂ to SO_3:

	is thermodynamically favourable, but is slow under ambient conditions
	is thermodynamically unfavourable under ambient conditions
	has a low activiation energy under ambient conditions
	is explosive under ambient conditions, and the reaction must be controlled on an industrial scale

What would be the main reason for replacing the PPh₃ ligands in a catalyst by P(C₆H₄SO₃^-)₃ ligands?

	To increase the leaving group ability of the ligand
	To increase the steric demands of the ligand, making it harder to replace
	To increase the water solubility of the catalyst
	To increase the solubility of the catalyst in organic solvents

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