Chapter 12 Test

Question 1

What term refers to the intermolecular attraction between molecules of the same compound?

Answer 1

Cohesion

Question 2

Look at these two different phase diagrams. Notice that the boundary between the solid and liquid phases for Substance B has a positive slope (tilts to the right) while the boundary between the solid and liquid phases for Substance A has a negative slope (tilts to the left). Given this information, which of the following statements is true?

Answer 2

For Substance B, there is some temperature at which it is possible to go from gas to liquid to solid by application of pressure.

Question 3

On the phase diagram shown, the pressure applied to a sample of water is raised from A to B. Describe what happens.

Answer 3

As the pressure on the sample passes through the boundary, the water changes from a solid to a liquid

Question 4

What is the critical point?

Answer 4

The temperature and pressure above which the distinction between liquid and gas disappears.

Question 5

What other information, in addition to the spacing between planes of particles, can be obtained from the X-ray diffraction pattern of a crystal?

Answer 5

From the intensities of the spots, we can determine the actual positions of atoms in the crystal.

Question 6

Titanium crystallizes on a body-centered cubic lattice with a unit cell edge length of 3.28 Å. The density of titanium is 4.54 g / cm3. The atomic mass of titanium is 47.88. Using this information, calculate Avogadro’s number.

Answer 6

5.98 × 10^23

Question 7

A silver crystal has a face-centered cubic unit cell. This is the closest silver atoms can be packed. What fraction of the unit cell in a silver crystal is empty space? The radius of a silver atom is 144 pm (though you don’t technically need this number to answer the question).

Answer 7

26%

Question 8

The radius of a silver atom is 144 pm. Silver forms a face-centered cubic crystal. What is the length of the unit cell in a silver atom?

Answer 8

407 pm

Question 9

Which of the following does not play a role in determining when a phase change occurs?

Answer 9

the amount of compound

Question 10

Generally speaking, which type of intermolecular attraction is the strongest?

Answer 10

ion-ion attraction

Question 11

What are intermolecular forces?

Answer 11

The forces between different molecules of a substance

Question 12

Arrange the following phases of matter in increasing degrees of freedom.

Answer 12

Solid, liquid, gas

Question 13

Which of the following is the best definition for equilibrium vapor pressure?

Answer 13

The pressure exerted at a given temperature by a vapor in equilibrium with the same substance in liquid form.

Question 14

What is superheated water?

Answer 14

Water that is heated above the normal boiling temperature at the given pressure

Question 15

Diamond is a covalent network solid. This means that each atom in a crystal of diamond ___________ .

Answer 15

shares electrons with all the surrounding atoms, forming covalent bonds

Question 16

Capillary action is the result of the minimization of surface area.

Answer 16

false

Question 17

At room temperature, iodine is a solid, bromine is a liquid and chlorine is a gas? Why is this?

Answer 17

London dispersion forces increase because electron polarizability increases as you go down a column

Question 18

In hydrogen bonding, what is the hydrogen bond acceptor?

Answer 18

A highly electronegative atom with at least one lone pair

Question 19

Which of the following polar substances does not exhibit strong hydrogen bonding?

Answer 19

Ammonia

Question 20

What happens to the vapor pressure at equilibrium when the volume is increased?

Answer 20

Volume has no effect on equilibrium vapor pressure.

Question 21

Is it possible for a solid, like iodine, that passes from the solid phase to the gas phase directly to have an equilibrium vapor pressure?

Answer 21

Yes, because some molecules of iodine must have sufficient energy to overcome intermolecular forces and escape to the gas phase

Question 22

Mica is a crystal that occurs in thin sheets. This is because the particles in mica have strong bonds within certain planes of particles, but very weak bonds between these planes. So mica is said to “cleave” very easily. The spacing between these weakly bonded layers in mica is 997 pm. At what angle would first order diffraction occur using X-rays of 154 pm?

Answer 22

4.43°

Question 23

Which of the following substances most likely has a periodic lattice structure?

Answer 23

Crystalline solids

Question 24

What are the two general types of solids?

Answer 24

Crystal and amorphous

Question 25

A single crystal is sliced very thin and the slice is placed in a beam of X-rays. The X-rays pass through the crystal and shine on a piece of photographic film. When the film is developed, what does the image look like?

Answer 25

The image consists of a regular, complex pattern of dots around a bright central image