Chemistry: Exam 4 Practice Test

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What is the oxidation number of gold in K3[Au(CN)4]?

+1

Given the following average bond energies: C-H = 415; Cl-Cl = 243; C-Cl = 330; H-Cl = 432

-104 kJ

Iron(III) forms an octahedral complex with the ligand CN-. How many unpaired electrons are in the dorbitals of iron?

1

Predict the bond order for F2+ according to the molecular orbital theory.

1.5

What is the bond order in Be2+

1/2

What is the approximate COH bond angle in the amino acid molecule below?

107°

The angle between sp3 hybrid orbitals is about

109°

The angle between sp2 hybrid orbitals is about

120°

Given that the average bond energies for C-H and C-Br bonds are 413 kJ/mol and 276 kJ/mol respectively, calculate the heat of atomization (breaking into atoms) of bromoform, CHBr3 .

1241 kJ/mol

How many lone pairs are found in the entire molecule PBr5?

15

What is the bond order in O2?

2

When K[Ag(CN)2] dissolves in water how many different ions will be present in solution?

2 ions

The sp2 hybrid orbital is constructed from how many atomic orbitals?

3

In the compound K[Co(C2O4)2(H2O)2] (where C2O42- = oxalate) the oxidation number and coordination number of cobalt are, respectively:

3 and 6

How many sigma and pi bonds are there in F2C=O?

3 sigma bonds and 1 pi bond

The total number of valence electrons in the sulfate ion, SO42-, is

32

In the complex ion [ML4]n+, Mn+ has six d-electrons and L is a weak field ligand. According to crystal field theory, the magnetic properties of the complex ion correspond to how many unpaired electrons?

4

How many atoms can bond to a central atom if the shape of the molecule is trigonal bipyramidal?

5

The number of valence electrons in an arsenic atom is

5

What is the coordination number of cobalt in the complex [Co(en)(NH3)2Br2]Cl?

6

What is the coordination number of cobalt in the complex ion [Co(en)Cl4]-? (en = ethylenediamine)

6

How many sigma and pi bonds does acetone (CH3COCH3) contain?

9 sigma bonds and 1 pi bond

The F-Xe-F angle in XeF4 is about

90°

The smallest angle between sp3d hybrid orbitals is

90°

Which of the following atoms can readily form covalent molecules with less than an octet of electrons?

B

Which one of the following is a bidentate ligand?

C2O42-

Which of the following substances will have hydrogen bonds between molecules?

CH3CH2-OH

Which of the following cannot function as a ligand?

CH4

Which of the following has the greatest polarizability?

CI4

Which of the following should have the highest boiling point?

CI4

Which one of the following ligands will lead to a complex in which the spin pairing energy is smaller than triangle in an octahedral complex?

CN-

Predict the order of increasing bond length for CN, CN-, and CN+.

CN- < CN < CN+

Which of the following is arranged in order of increasing molecular dipole moment?

Cl2 = CO2 < NH3

Which of the molecules below contain the shortest carbon-carbon distance?

H-C (triple bonded) C-H

All of the following ligands are monodentate except

H2N(CH2)2NH2

Which has the smallest bond angle?

H2O

Neon condenses due to

London dispersion forces.

The strongest intermolecular interactions between pentane (C5H12) molecules arise from

London dispersion forces.

Which of the following ions could exist in either the high-spin or low-spin state in an octahedral complex?

Mn2+

Which of the following has the largest bond dissociation energy?

N2

Which one of the following molecules is polar?

NCl3

Which of the following is most likely paramagnetic?

NO

Predict which of the following is paramagnetic?

NO2

Which of the following cannot form both a high spin and a low spin octahedral complex ion?

Ti2+

Appreciable pi bonding character is found in which of the following?

acetylene - C2H2, ethylene gas - C2H4, carbon dioxide

Linear geometry best describes which of the following molecules?

acetylene, C2H2

Polar molecules

align with an external electric field and have net dipole moments

The bonding between C atoms in the following molecule is best described by H2C = C = NH

SIGMA:C sp2, C sp PI:C p, C p

An element, X, forms an XF62- ion with fluorine. If there are no nonbonding electrons on X in the Lewis structure, the element X could be

Si

Diamagnetic species

are pushed out of a magnetic field.

A transition metal complex absorbs light in the orange region of the spectrum. What color is it?

blue

In hydrogen iodide __________________ are the most important intermolecular forces.

dipole-dipole forces

The CO32- ion is stabilized by

electron delocalization.

The ground state electron configuration of Cr2+ is

[Ar]3d4

Write the formula for diamminedichloroethylenediaminecobalt(III) bromide

[CoCl2(en)(NH3)2]Br

The compound tetraamminecopper(II) hexacyanoferrate(III) has the formula

[Cu(NH3)4]3[Fe(CN)6]2

Predict the absorption of light in order of increasing wavelength for the complexes below. [MnF6]4- [Mn(H2O)6]2+ [Mn(NH3)6]

[Mn(NH3)6]2+ < [Mn(H2O)6]2+ < [MnF6]4-

The greatest electronic repulsions in a molecule occur between

lone pairs

A typical triple bond consists of

one sigma and two pi bonds

According to valence bond theory, the triple bond in ethyne (acetylene, C2H2) consists of

one σ bond and two π bonds.

What is the name of the complex Na[Co(NH3)3Cl3]?

sodium triamminetrichlorocobaltate(II)

What is the hybridization of the carbon bonded to nitrogen? H2C=C=NH

sp

The hybridization of P in PF5 is

sp3d

The hybridization of the Xe atom in XeF2 is

sp3d

What is the hybridization on the central atom in ICl4- ?

sp3d2

The general requirements for bond formation according to valence bond theory include

spatial overlap of orbitals and similarity in energy of overlapping orbitals.


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