Chemistry: Exam 4 Practice Test
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.
