Question 1

Examine the following phase diagram and determine what phase exists at point F.

Accepted Answer

A) vapor + liquid 
B) vapor 
C) liquid 
D) solid 
E) supercritical fluid

Question 2

Examine the phase diagram for the substance Bogusium (Bo)and select the correct statement.

Accepted Answer

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.

Question 3

The surface tension of water is lowered when a detergent is present in solution.

Accepted Answer

A) True 
 B)False

Question 4

Iron crystallizes in the body-centered cubic lattice.What is the coordination number for Fe?

Accepted Answer

A) 4 
B) 6 
C) 8 
D) 10 
E) 12

Question 5

A temperature increase causes __________________ in the conductivity of a conductor.

Accepted Answer

A) a decrease 
B) an increase 
C) an increase or decrease (depending on the conductor) 
D) a modulation 
E) no change

Question 6

In cubic closest packing,the unit cell is body-centered cubic.

Accepted Answer

A) True 
 B)False

Question 7

Which of the following terms refers to the resistance of a liquid to flow?

Accepted Answer

A) surface tension 
B) capillary action 
C) viscosity 
D) adhesion 
E) cohesion

Question 8

Chlorine trifluoride is used in processing nuclear reactor fuel.It has a vapor pressure of 29.1 torr at -47.0°C and its heat of vaporization is 30.61 kJ/mol.At what temperature would its vapor pressure be 107.7 torr?

Accepted Answer

The answer of Chlorine trifluoride is used in processing nuclear...

Question 9

How do the electrical properties of semiconductors differ from those of metals?

Accepted Answer

The answer of How do the electrical properties of semiconductors...

Question 10

Select the pair of substances in which the one with the lower vapor pressure at a given temperature is listed first.

Accepted Answer

A) a 
B) b 
C) c 
D) d 
E) e

Question 11

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?

Accepted Answer

A) Ek(g)k(l);Ep(g)$\approx$ Ep(l) 
B) Ek(g)> Ek(l);Ep(g) $\approx$ Ep(l) 
C) Ep(g)p(l);Ek(g) $\approx$ Ek(l) 
D) Ep(g)> Ep(l);Ek(g) $\approx$ Ek(l) 
E) Ep(g)$\approx$ Ep(l);Ek(g)$\approx$ Ek(l)

Question 12

The vapor pressure of 1-butene is 1.268 atm at 273.15 K and its heat of vaporization is 22.9 kJ/mol.What is the normal boiling point of 1-butene?

Accepted Answer

The answer of The vapor pressure of 1-butene is 1.268...

Question 13

Liquid ammonia boils at -33.4°C and has a heat of vaporization of 23.5 kJ/mol.Calculate its vapor pressure at -50.0°C.

Accepted Answer

The answer of Liquid ammonia boils at -33.4°C and has...

Question 14

Which of the following should have the lowest boiling point?

Accepted Answer

A) C5H12 
B) C6H14 
C) C8H18 
D) C10H22 
E) C12H26

Question 15

Octane is a component of fuel used in internal combustion engines.The dominant intermolecular forces in octane are

Accepted Answer

A) dipole-dipole forces. 
B) London dispersion forces. 
C) hydrogen bonding. 
D) covalent bonds. 
E) carbon-hydrogen bonds.

Question 16

a.Explain what is meant by the term "unit cell". b.Copper metal has a face-centered cubic unit cell.The edge length of the unit cell is 361 pm,and the atomic weight of copper is 63.55 amu.Calculate the density of the copper in g/cm³. (1 amu = 1.661 $\times$ 10^-24 g. ) c.From the data in (b),calculate the radius of a copper atom in pm.

Accepted Answer

The answer of a.Explain what is meant by the term...

Question 17

In hydrogen iodide __________________ are the most important intermolecular forces.

Accepted Answer

A) dipole-dipole forces 
B) London dispersion forces 
C) hydrogen bonding 
D) covalent bonds 
E) polar covalent bonds

Question 18

Mercury melts at -39°C and boils at 357°C.Draw a diagram of the heating curve of mercury.Label all lines and axes,and clearly indicate the melting and boiling points on your diagram.

Accepted Answer

The answer of Mercury melts at -39°C and boils at...

Question 19

Assuming that atoms are spherical,calculate the fraction of space which is occupied by atoms (i.e. ,the packing efficiency)in a metal with a face-centered cubic unit cell.

Accepted Answer

The answer of Assuming that atoms are spherical,calculate the fraction...

Question 20

Which of the following liquid substances would you expect to have the lowest surface tension?

Accepted Answer

A) Pb 
B) CH3OCH3 
C) HOCH2CH2OH 
D) H2O 
E) CH3CH2OH

Exam 12: Intermolecular Forces: Liquids,solids,and Phase Changes