Exam 1 CHM Flashcards
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) Ep(l); Ek(g) ≈ Ek(l) B) Ek(g) > Ek(l); Ep(g) ≈ Ep(l) E) Ep(g) ≈ Ep(l); Ek(g) ≈ Ek(l) C) Ep(g) Ep(l); Ek(g) ≈ Ek(l)
Ep(g)
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) C) 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)
Ek(40°C) > Ek(20°C); Ep(40°C) ≈ Ep(20°C)
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.
50.0 torr
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 D) heat of fusion B) boiling point E) heat of vaporization C) triple point
triple point
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 the above statements is true.
Solid xenon has a higher density than liquid xenon.
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 NH3(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
39 kJ
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
-48.6 kJ
A 5.00 g sample of water vapor, initially at 155°C is cooled at atmospheric pressure, producing ice at –55°C. Calculate the amount of heat energy lost by the water sample in this process, in kJ. Use the following data: specific heat capacity of ice is 2.09 J/g⋅K; specific heat capacity of liquid water is 4.18 J/g⋅K; specific heat capacity of water vapor is 1.84 J/g⋅K; heat of fusion of ice is 336 J/g; heat of vaporization of water is 2260 J/g.
A) 15.6 kJ B) 10.2 kJ C) 5.4 kJ D) 16.2 kJ E) 1.6 kJ
16.2 kJ
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 D) 710 kJ/mol B) 46.0 kJ/mol E) none of the above C) 590 kJ/mol
39.0 kJ/mol
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 D) 1.00 × 10^2 kJ/mol B) 52.5 kJ/mol E) none of the above C) 70.6 kJ/mol
1.00 x 10^2 kj/Mol
The Clausius-Clapeyron equation is used in calculations of A) melting and freezing points. B) vapor pressures of liquids. C) osmotic pressures of solutions. D) heats of vaporization at different temperatures. E) crystal structure.
vapor pressure of liquids
The normal boiling point of ether is 307.8 K. Calculate the temperature at which its vapor pressure is exactly half of that at its normal boiling point. The heat of vaporization for ether is 26.69 kJ/mol.
A) 305 K B) 302 K C) 295 K D) 289 K E) 281 K
289 K
Neon atoms are attracted to each other by A) dipole-dipole forces. D) covalent bonding. B) London dispersion forces. E) intramolecular forces. C) hydrogen bonding.
London dispersion
Ammonia's unusually high melting point is the result of A) dipole-dipole forces. D) covalent bonding. B) London dispersion forces. E) ionic bonding. C) hydrogen bonding.
hydrogen bonding
Octane is a component of fuel used in internal combustion engines. The dominant intermolecular forces in octane are A) dipole-dipole forces. D) covalent bonds. B) London dispersion forces. E) carbon-hydrogen bonds. C) hydrogen bonding.
London dispersion
In hydrogen iodide \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ are the most important intermolecular forces. A) dipole-dipole forces D) covalent bonds B) London dispersion forces E) polar covalent bonds C) hydrogen bonding
dipole-dipole
When the electron cloud of a molecule is easily distorted, the molecule has a high \_\_\_\_\_\_\_\_\_\_\_\_\_. A) polarity D) van der Waals radius B) polarizability E) compressibility C) dipole moment
polarizability
Which of the following atoms should have the greatest polarizability?
A) F B) Br C) Po D) Pb E) He
Pb
Which of the following atoms should have the smallest polarizability?
A) Si B) S C) Te D) Bi E) Br
S
The strongest intermolecular interactions between pentane (C5H12) molecules arise from A) dipole-dipole forces. D) ion-dipole interactions. B) London dispersion forces. E) carbon-carbon bonds. C) hydrogen bonding.
london-dispersion
What types of forces exist between molecules of CO2? A) hydrogen bonding only. B) hydrogen bonding and dispersion forces. C) dipole-dipole forces only. D) dipole-dipole and dispersion forces. E) dispersion forces only.
dispersion forces only
The strongest intermolecular interactions between ethyl alcohol (CH3CH2OH) molecules arise from A) dipole-dipole forces. D) ion-dipole interactions. B) London dispersion forces. E) carbon-oxygen bonds. C) hydrogen bonding.
hydrogen bonding
The strongest intermolecular interactions between hydrogen sulfide (H2S) molecules arise from A) dipole-dipole forces. D) ion-dipole interactions. B) London dispersion forces. E) disulfide linkages. C) hydrogen bonding.
dipole-dipole
The strongest intermolecular interactions between hydrogen fluoride (HF) molecules arise from A) dipole-dipole forces. D) ion-dipole interactions. B) London dispersion forces. E) ionic bonds. C) hydrogen bonding.
hydrogen bonding
Which one 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
CH3CH2–OH
Which of the following pairs of molecules can form hydrogen bonds between them? A) HCl and HI D) SO2 and CH2O B) CH3OH and NH3 E) H2 and O2 C) CH4 and H2O
CH3OH and NH3
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 the above
Se2–, S2–
Which of the following pairs is arranged with the particle of higher polarizability listed first? A) CCl4, CI4 D) NH3, NF3 B) H2O, H2Se E) none of the above C) C6H14, C4H10
C6H14, C4H10
Which of the following should have the highest boiling point?
A) CF4 B) CCl4 C) CBr4 D) CI4 E) CH4
CI4
Which of the following should have the lowest boiling point?
A) C5H12 B) C6H14 C) C8H18 D) C10H22 E) C12H26
C5H12
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
NH3
Select the pair of substances in which the one with the higher vapor pressure at a given temperature is listed first. A) C7H16, C5H12 D) CH3CH2OH, CH3–O–CH3 B) CCl4, CBr4 E) Xe, Kr C) H2O, H2S
CCl4, CBr4
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 D) dipole-dipole B) dipole-induced dipole E) dispersion C) ion-dipole
ion-dipole
Which of the following should have the highest surface tension at a given temperature?
A) CH4 B) CF4 C) CCl4 D) CBr4 E) CI4
Cl4
Which of the following properties measures the energy needed to increase the surface area of a liquid? A) capillary action D) cohesion B) surface tension E) specific elasticity C) viscosity
surface tension
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 the above will occur.
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.
The meniscus of mercury in a glass capillary tube is convex because of
A)
the very high density of mercury as compared with water.
B)
the low surface tension of mercury.
C)
the greater attraction of mercury atoms to the glass than to each other.
D)
the weaker attraction of mercury atoms to the glass than to each other.
E)
electrostatic repulsion between the glass and the mercury.
the greater attraction of mercury atoms to the glass than to each other.
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
viscosity
Which of the following factors contributes to a low viscosity for a liquid? A) low temperature D) high molecular weight B) spherical molecular shape E) high boiling point C) hydrogen bonding
spherical molecular shape
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
CH3OCH3
Which of the following liquids is likely to have the highest surface tension?
A) Br2 B) C8H18 C) CH3OCH3 D) CH3OH E) Pb
Pb
When identical particles pack in a simple cubic lattice, there is/are ____ particle(s) per unit cell.
A) 1 B) 2 C) 3 D) 4 E) 8
1
A metal with a body-centered cubic lattice will have ______ atom(s) per unit cell.
A) 1 B) 2 C) 3 D) 4 E) 9
2
A metal such with a face-centered cubic lattice will have ________________ atom(s) per unit cell.
A) 1 B) 2 C) 3 D) 4 E) 10
4
Polonium crystallizes in the simple cubic lattice. What is the coordination number for Po?
A) 3 B) 4 C) 6 D) 8 E) 12
6
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
8
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
12
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.
The faces of a unit cell must all be at angles of 90° to each other.
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.
The coordination number of the atoms in the lattice is 8.
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 bcc structure has a higher packing efficiency than a fcc structure.
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.
693
A certain solid metallic element has a density 7.87 g/cm3 and a molar mass of 55.85 g/mol. It crystallizes with a cubic unit cell, with an edge length of 286.7 pm. Calculate the number of atoms per unit cell.
A) 1 B) 2 C) 3 D) 4 E) 6
2
Crystal structures may be conveniently measured using A) X-ray diffraction. D) microwave spectroscopy. B) infrared spectroscopy. E) magnetic resonance imaging. C) ultraviolet-visible spectroscopy.
x-ray diffraction
Which one of the following substances does not exist in the indicated solid type? A) graphite - network D) NaCl - ionic B) Na - metallic E) diamond - network C) SiO2 - molecular
SiO2-molecular
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
molecular
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
S
What adjective best describes the solid compound IF7? A) metallic B) amorphous C) covalent network D) molecular E) ionic
molecular