Chem Final Study

f

(T/F) A single water molecule can participate in at most two hydrogen bonds at any instant.

f

(T/F) Hexagonal close packing of identical atoms occurs when close-packed layers are stacked in an abcabc.... arrangement.

f

(T/F) In cubic closest packing, the unit cell is body-centered cubic.

f

(T/F) In metals, the conduction bands and valence bands of the molecular orbitals are separated by a large energy gap.

t

(T/F) In the packing of identical atoms with cubic unit cells, the packing efficiency increases as the coordination number increases.

f

(T/F) Only molecules which do not have dipole moments can experience dispersion forces.

f

(T/F) The energy of a hydrogen bond is greater than that of a typical covalent bond.

f

(T/F) The maximum number of phases of a single substance which can coexist in equilibrium is two.

t

(T/F) The surface tension of water is lowered when a detergent is present in solution.

d

A cubic unit cell has an edge length of 400. pm. The length of its body diagonal (internal diagonal) in pm is therefore A) 512 B) 566 C) 631 D) 693 E) 724

a

A metal in the simple cubic lattice will have ________________ atom(s) per unit cell. A) 1 B) 2 C) 3 D) 4 E) 8

b

A metal such as chromium in the body-centered cubic lattice will have _______________ atom(s) per unit cell. A) 1 B) 2 C) 3 D) 4 E) 9

d

A metal such as chromium in the face-centered cubic lattice will have ________________ atom(s) per unit cell. A) 1 B) 2 C) 3 D) 4 E) 10

b

A molecule with the formula AX₃ uses __________ to form its bonds. A) sp hybrid orbitals B) sp² hybrid orbitals C) sp³ hybrid orbitals D) sp³d hybrid orbitals E) sp³d² hybrid orbitals

b

A molecule with the formula AX₃E uses _________ to form its bonds. A) s and p atomic orbitals B) sp³ hybrid orbitals C) sp² hybrid orbitals D) sp hybrid orbitals E) sp³d₂ hybrid orbitals

c

A molecule with the formula AX₄ uses _________ to form its bonds. A) sp hybrid orbitals B) sp² hybrid orbitals C) sp³ hybrid orbitals D) sp³d hybrid orbitals E) sp³d² hybrid orbitals

b

A sample of octane in equilibrium with its vapor in a closed 1.0-L container has a vapor pressure of 50.0 torr at 45°C. The container's volume is increased to 2.0 L at constant temperature and the liquid/vapor equilibrium is reestablished. What is the vapor pressure? A) >50.0 torr B) 50.0 torr C) 25.0 torr D) The mass of the octane vapor is needed to calculate the vapor pressure. E) The external pressure is needed to calculate the vapor pressure.

B

A temperature increase causes __________________ in the conductivity of a semiconductor. A) a decrease B) an increase C) a modulation D) an increase or decrease (depending on the semiconductor) E) no change

a

A temperature increase causes __________________ in the conductivity of a conductor. A) a decrease B) an increase C) an increase or decrease (depending on the conductor) D) a modulation E) no change

a

According to VSEPR theory, a molecule with the general formula AX2 will have a ___ molecular shape. A) linear B) bent C) trigonal planar D) tetrahedral E) triangular

c

According to VSEPR theory, a molecule with the general formula AX3 will have a ______ molecular shape. A) linear B) bent C) trigonal planar D) tetrahedral E) trigonal pyramidal

e

According to VSEPR theory, a molecule with the general formula AX4 will have a ______ molecular shape. A) bent B) trigonal planar C) trigonal pyramidal D) square planar E) tetrahedral

d

According to VSEPR theory, a molecule with the general formula AX5 will have a ______ molecular shape. A) tetrahedral B) trigonal planar C) trigonal pyramidal D) trigonal bipyramidal E) see-saw

e

According to VSEPR theory, a molecule with the general formula AX6 will have a ______ molecular shape. A) tetrahedral B) trigonal planar C) trigonal bipyramidal D) hexagonal E) octahedral

d

According to molecular orbital (MO) theory, the twelve outermost electrons in the O2 molecule are distributed as follows: A) 12 in bonding MOs, 0 in antibonding MOs. B) 10 in bonding MOs, 2 in antibonding MOs. C) 9 in bonding MOs, 3 in antibonding MOs. D) 8 in bonding MOs, 4 in antibonding MOs. E) 7 in bonding MOs, 5 in antibonding MOs.

d

According to molecular orbital theory, what is the bond order in the O₂⁺ ion? A) 5.5 B) 5 C) 4 D) 2.5 E) 1.5

c

According to valence bond theory, the triple bond in ethyne (acetylene, C2H2) consists of A) three σ bonds and no π bonds. B) two σ bonds and one π bond. C) one σ bond and two π bonds. D) no σ bonds and three π bonds. E) None of these choices is correct.

c

Ammonia's unusually high melting point is the result of A) dipole-dipole forces. B) London dispersion forces. C) hydrogen bonding. D) covalent bonding. E) ionic bonding.

c

Comparing the energies of the following intermolecular forces on a kJ/mol basis, which would normally have the highest energy (i.e., be the strongest force)? A) ion-induced dipole B) dipole-induced dipole C) ion-dipole D) dipole-dipole E) dispersion

b

Consider the following phase diagram and identify the process occurring as one goes from point C to point D. SEE QUESTION 13 Image A) increasing temperature with a phase change from solid to liquid B) increasing temperature with a phase change from solid to vapor C) increasing temperature with a phase change from liquid to vapor D) increasing temperature with no phase change E) increasing temperature beyond the critical point

e

Diethyl ether, used as a solvent for extraction of organic compounds from aqueous solutions, has a high vapor pressure which makes it a potential fire hazard in laboratories in which it is used. How much energy is released when 100.0 g is cooled from 53.0°C to 10.0°C? boiling point - 34.5°C heat of vaporization - 351 J/g specific heat capacity, (CH₃)₂O(l) - 3.74 J/(g·K) specific heat capacity, (CH₃)₂O(g) - 2.35 J/(g·K) A) 10.1 kJ B) 13.1 kJ C) 16.1 kJ D) 45.2 kJ E) 48.6 kJ

b

Examine the following phase diagram and determine what phase exists at point F. SEE QUESTION 14 Image A) vapor + liquid B) vapor C) liquid D) solid E) supercritical fluid

c

Examine the following phase diagram and identify the feature represented by point A. SEE QUESTION 11 image A) melting point B) critical point C) triple point D) sublimation point E) boiling point

c

Examine the following phase diagram and identify the feature represented by point B. SEE QUESTION 12 image A) melting point B) triple point C) critical point D) sublimation point E) boiling point

e

Examine the phase diagram for the substance Bogusium (Bo) and select the correct statement. SEE QUESTION 10 Image A) Bo(s) has a lower density than Bo(l). B) The triple point for Bo is at a higher temperature than the melting point for Bo. C) Bo changes from a solid to a liquid as one follows the line from C to D. D) Bo changes from a liquid to a gas as one follows the line from C to D. E) Point B represents the critical ⁺temperature and pressure for Bo.

d

For the solid forms of the following elements, which one is most likely to be of the molecular type? A) Xe B) C C) Pb D) S E) Cr

a

For which one of the following molecules is the indicated type of hybridization not appropriate for the central atom? A) BeCl₂ sp² B) SiH₄ sp³ C) BF₃ sp² D) C₂H₂ sp E) H₂O sp³

e

In an ionic solid MX consisting of the monatomic ions, M + and X - , the coordination number of M + is _______________. A) 1 B) 2 C) 6 D) 8 E) impossible to predict without knowing the crystal structure of MX

a

In hydrogen iodide __________________ are the most important intermolecular forces. A) dipole-dipole forces B) London dispersion forces C) hydrogen bonding D) covalent bonds E) polar covalent bonds

c

In which of the following compounds will the molecules not form hydrogen bonds with each other? SEE QUESTION 27 Image A) a B) b C) c D) d E) e

e

In which one of the following species is the central atom (the first atom in the formula) an exception to the octet rule? A) NH₃ B) NH₄⁺ C) I₂ D) BH₄⁻ E) SF⁶

c

Iron crystallizes in the body-centered cubic lattice. What is the coordination number for Fe? A) 4 B) 6 C) 8 D) 10 E) 12

e

Lead crystallizes in the face-centered cubic lattice. What is the coordination number for Pb? A) 4 B) 6 C) 8 D) 10 E) 12

c

Liquid ammonia (boiling point = -33.4°C) can be used as a refrigerant and heat transfer fluid. How much energy is needed to heat 25.0 g of NH 3 (l) from -65.0°C to -12.0°C? Specific heat capacity, NH₃(l) - 4.7 J/(g·K) Specific heat capacity, NH₃(g) - 2.2 J/(g·K) Heat of vaporization - 23.5 kJ/mol Molar Mass = 17.0 g/mol A) 5.5 kJ B) 6.3 kJ C) 39 kJ D) 340 kJ E) 590 kJ

d

Liquid sodium can be used as a heat transfer fluid. Its vapor pressure is 40.0 torr at 633°C and 400.0 torr at 823°C. Calculate its heat of vaporization. A) 43.4 kJ/mol B) 52.5 kJ/mol C) 70.6 kJ/mol D) 1.00 x 10² kJ/mol E) None of these choices is correct.

b

Neon condenses due to A) dipole-dipole forces. B) London dispersion forces. C) hydrogen bonding. D) covalent bonding. E) intramolecular forces.

a

Octane has a vapor pressure of 40. torr at 45.1°C and 400. torr at 104.0°C. What is its heat of vaporization? A) 39.0 kJ/mol B) 46.0 kJ/mol C) 590 kJ/mol D) 710 kJ/mol E) None of these choices is correct.

b

Octane is a component of fuel used in internal combustion engines. The dominant intermolecular forces in octane are A) dipole-dipole forces. B) London dispersion forces. C) hydrogen bonding. D) covalent bonds. E) carbon-hydrogen bonds.

c

One can safely assume that the 3s- and 3p-orbitals will form molecular orbitals similar to those formed when 2s- and 2p-orbitals interact. According to molecular orbital theory, what will be the bond order for the Cl₂⁺ ion? A) 0.5 B) 1 C) 1.5 D) 2 E) None of these choices is correct.

d

Pentane, C₅H₁₂ , boils at 35°C. Which of the following is true about kinetic energy, Ek, and potential energy, Ep, when liquid pentane at 35°C is compared with pentane vapor at 35°C? A) Ek (g) <Ek (l); Ep (g) ≈ Ep (l) B) Ek (g) > Ek (l); Ep (g) ≈ Ep (l) C) Ep (g) < Ep (l); Ek (g) ≈ Ek (l) D) Ep (g) > Ep (l); Ek (g) ≈ Ek (l) E) Ep (g) ≈ Ep (l); Ek (g) ≈ Ek (l)

c

Polonium crystallizes in the simple cubic lattice. What is the coordination number for Po? A) 3 B) 4 C) 6 D) 8 E) 12

c

Predict the actual bond angle in SeCl2 using the VSEPR theory. A) more than 120° B) between 109° and 120° C) between 90° and 109° D) exactly 90° E) less than 90°

b

Predict the ideal bond angles in AsCl3 using the molecular shape given by the VSEPR theory. A) 90° B) 109° C) 120° D) 180° E) between 110 and 120°

b

Predict the ideal bond angles in GeCl4 using the molecular shape given by the VSEPR theory. A) 90° B) 109° C) 120° D) 180° E) < 90°

a

Select the correct Lewis structure for nitrogen trifluoride, NF3. SEE QUESTION 2 QUIZ image A) a B) b C) c D) d E) e

b

Select the pair of substances in which the one with the higher vapor pressure at a given temperature is listed first. A) C₇H₁₆, C₅H₁₂ B) CCl₄, CBr₄ C) H₂O, H₂S D) CH₃CH₂OH, CH₃-O-CH₃ E) Xe, Kr

a

Select the pair of substances in which the one with the lower vapor pressure at a given temperature is listed first. SEE QUESTION 34 Image A) a B) b C) c D) d E) e

c

The coordination number of sodium and chloride ions in the NaCl lattice, are, respectively: A) 10 and 10 B) 8 and 8 C) 6 and 6 D) 4 and 4 E) None of these choices is correct.

d

The energy gap between the conduction band and the valence band is large for A) conductors. B) semiconductors. C) superconductors. D) insulators. E) alloys.

b

The energy needed to increase the surface area of a liquid is A) capillary action. B) surface tension. C) viscosity. D) cohesion. E) specific elasticity.

e

The highest temperature at which superconductivity has been achieved is approximately A) 4 K B) 30 K C) 70 K D) 100 K E) 130 K

a

The phase diagram for xenon has a solid-liquid curve with a positive slope. Which of the following is true? A) Solid xenon has a higher density than liquid xenon. B) Solid xenon has the same density as liquid xenon. C) The phase diagram cannot be used to predict which phase of xenon is denser. D) Freezing xenon is an endothermic process. E) None of these statements is true.

c

The strongest intermolecular interactions between ethyl alcohol (CH₃CH₂OH) moleculesarise from A) dipole-dipole forces. B) London dispersion forces. C) hydrogen bonding. D) ion-dipole interactions. E) carbon-oxygen bonds.

c

The strongest intermolecular interactions between hydrogen fluoride (HF) molecules arise from A) dipole-dipole forces. B) London dispersion forces. C) hydrogen bonding. D) ion-dipole interactions. E) ionic bonds.

a

The strongest intermolecular interactions between hydrogen sulfide (H 2 S) molecules arise from A) dipole-dipole forces. B) London dispersion forces. C) hydrogen bonding. D) ion-dipole interactions. E) disulfide linkages.

b

The strongest intermolecular interactions between pentane (C 5 H 12 ) molecules arise from A) dipole-dipole forces. B) London dispersion forces. C) hydrogen bonding. D) ion-dipole interactions. E) carbon-carbon bonds.

e

What is the molecular shape of N2O as predicted by the VSEPR theory? SEE QUESTION 9 QUIZ Image A) trigonal pyramidal B) trigonal planar C) angular D) bent E) linear

e

What is the molecular shape of SiF₆²⁻ as predicted by the VSEPR theory? SEE QUESTION 10 QUIZ Image A) trigonal bipyramidal B) hexagonal C) tetrahedral D) see-saw E) octahedral

c

When liquid bromine is cooled to form a solid, which of the following types of solid would it form? A) atomic B) metallic C) molecular D) ionic E) covalent network

b

When the adhesive forces between a liquid and the walls of a capillary tube are greater than the cohesive forces within the liquid A) the liquid level in a capillary tube will rise above the surrounding liquid and the surface in the capillary tube will have a convex meniscus. B) the liquid level in a capillary tube will rise above the surrounding liquid and the surface in the capillary tube will have a concave meniscus. C) the liquid level in a capillary tube will drop below the surrounding liquid and the surface in the capillary tube will have a convex meniscus. D) the liquid level in a capillary tube will drop below the surrounding liquid and the surface in the capillary tube will have a concave meniscus. E) None of these will occur.

b

When the electron cloud of a molecule is easily distorted, the molecule has a high A) polarity. B) polarizability. C) dipole moment. D) van der Waals radius. E) compressibility.

d

Which of the following atoms should have the greatest polarizability? A) F B) Br C) Po D) Pb E) He

b

Which of the following atoms should have the smallest polarizability? A) Si B) S C) Te D) Bi E) Br

b

Which of the following factors contributes to a low viscosity for a liquid? A) low temperature B) spherical molecular shape C) hydrogen bonding D) high molecular weight E) high boiling point

a

Which of the following has a boiling point which does not fit the general trend? A) NH₃ B) PH₃ C) AsH₃ D) SbH₃ E) BiH₃

d

Which of the following has no net dipole moment? A) N₂O B) NF₃ C) H₂Se D) TeO₃ E) CH₃Cl

b

Which of the following is true about kinetic energy, Ek , and potential energy, Ep , when ethyl alcohol at 40°C is compared with ethyl alcohol at 20°C? A) Ek (40°C) < Ek (20°C); Ep (40°C) ≈ Ep (20°C) B) Ek (40°C) > Ek (20°C); Ep (40°C) ≈ Ep (20°C) C) Ep (40°C) < Ep (20°C); Ek (40°C) ≈ Ek (20°C) D) Ep (40°C) > Ep (20°C); Ek (40°C) ≈ Ek (20°C) E) Ep (40°C) > Ep (20°C); Ek (40°C) > Ek (20°C)

b

Which of the following liquid substances would you expect to have the lowest surface tension? A) Pb B) CH₃OCH₃ C) HOCH₂CH₂OH D) H₂O E) CH₃CH₂OH

e

Which of the following liquids is likely to have the highest surface tension? A) Br₂ B) C₈H₁₈ C) CH ₃OCH₃ D) CH₃OH E) Pb

b

Which of the following molecules has a net dipole moment? A) BeCl₂ B) SF₂ C) KrF₂ D) CO₂ E) CCl₄

c

Which of the following pairs is arranged with the particle of higher polarizability listed first? A) CCl₄, CI₄ B) H₂O, H₂Se C) C₆H₁₄, C₄H₁₀ D) NH₃, NF₃ E) None of these choices is correct.

a

Which of the following pairs is arranged with the particle of higher polarizability listed first? A) Se²⁻ , S²⁻ B) I, I⁻ C) Mg²⁺ , Mg D) Br, I E) None of these choices is correct.

b

Which of the following pairs of substances is arranged so that the one with higher viscosity is listed first? SEE QUESTION 42 Image A) a B) b C) c D) d E) None of these choices is correct.

d

Which of the following should have the highest boiling point? A) CF₄ B) CCl₄ C) CBr₄ D) CI₄ E) CH₄

e

Which of the following should have the highest surface tension at a given temperature? A) CH 4 B) CF 4 C) CCl₄ D) CBr₄ E) CI₄

d

Which of the following should have the highest surface tension at a given temperature? SEE QUESTION 37 Image A) a B) b C) c D) d E) e

a

Which of the following should have the lowest boiling point? A) C₅H₁₂ B) C₆H₁₄ C) C₈H₁₈ D) C₁₀H₂₂ E) C₁₂H₂₆

e

Which of the following statements about the packing of monatomic solids with different unit cells is incorrect? A) The coordination number of atoms in hcp and fcc structures is 12. B) The coordination number of atoms in simple cubic structures is 6. C) The coordination number of atoms in bcc structures is 8. D) A bcc structure has a higher packing efficiency than a simple cubic structure. E) A bcc structure has a higher packing efficiency than a fcc structure.

a

Which of the following statements concerning a face-centered cubic unit cell and the corresponding lattice, made up of identical atoms, is incorrect? A) The coordination number of the atoms in the lattice is 8. B) The packing in this lattice is more efficient than for a body-centered cubic system. C) If the atoms have radius r, then the length of the cube edge is 8 r. D) There are four atoms per unit cell in this type of packing. E) The packing efficiency in this lattice and hexagonal close packing are the same.

c

Which of the following substances will have hydrogen bonds between molecules? A) (CH₃)₃N B) CH₃-O-CH₃ C) CH₃CH₂-OH D) CH₃CH₂-F E) HI

c

Which of the following terms refers to the resistance of a liquid to flow? A) surface tension B) capillary action C) viscosity D) adhesion E) cohesion

c

Which one of the following Lewis Structures is definitely incorrect? SEE QUESTION 1 QUIZ Image A) a B) b C) c D) d E) e

a

Which one of the following molecules does not have a dipole moment? A) CS₂ B) H₂S C) CH₂Cl₂ D) PH₃ E) CH₂O

c

Which one of the following quantities is generally not obtainable from a single heating or cooling curve of a substance, measured at atmospheric pressure? A) melting point B) boiling point C) triple point D) heat of fusion E) heat of vaporization

b

Which one of the following statements about unit cells and packing in solids is incorrect? A) In any unit cell of a solid crystal, each face of the cell must have an opposite face which is equal and parallel to it. B) The faces of a unit cell must all be at angles of 90° to each other. C) The coordination number of atoms in a close packed metal is 12. D) The packing efficiency in fcc structures is higher than in bcc structures. E) The packing efficiency in fcc and hcp structures is the same.

c

Which one of the following substances does not exist in the indicated solid type? A) graphite - network B) Na - metallic C) SiO₂- molecular D) NaCl - ionic E) diamond - network