Chapter 11 - Liquids and Intermolecular Forces

Question 0

What are the three types of van der Waals forces?

Answer 0

Dispersion forces, dipole-dipole attractions, and hydrogen bonding.

Question 1

What are condensed phases?

Answer 1

Solids and liquids.

Question 2

What is a dispersion force?

Answer 2

The motions of electrons in one atom influence the motions of electrons in its neighbors. This brief interaction is significant only when molecules are very close together.

Question 3

What is polarizability?

Answer 3

It is the ease with which the charge distribution (electron cloud) is distorted. More polarizable molecules have larger dispersion forces.

Question 4

What are dipole-dipole forces?

Answer 4

These forces originate from electrostatic attractions between a partially positive end of one molecule and the partially negative end of a molecule. It is effective only when molecules are very close together.

Question 5

What is a hydrogen bond?

Answer 5

It is an attraction between a hydrogen atom attached to a highly electronegative atom (usually F, O, or N) and a nearby small electronegative atom and another molecule or chemical group.

Question 6

What is an ion-dipole force?

Answer 6

It is a force that exists between an ion and a polar molecule.

Question 7

What is viscosity?

Answer 7

It is the resistance of a liquid to flow. The more it has, the more slowly it flows.

Question 8

What is surface tension?

Answer 8

It is the energy required to increase the surface area of a liquid by a unit amount.

Question 9

What are cohesive forces?

Answer 9

It is an intermolecular force that binds similar molecules to one another, such as hydrogen bonding in water.

Question 10

What is an adhesive force?

Answer 10

It is an intermolecular force that binds a substance to a surface.

Question 11

What is capillary action?

Answer 11

It is the ability of a liquid to flow in narrow spaces without the assistance of, and opposition to, external forces like gravity.

Question 12

What is a phase change?

Answer 12

It is simply a change of state, such as gas to liquid or liquid to solid.

Question 13

What is fusion?

Answer 13

It is the process of melting, from solid to liquid.

Question 14

What is vaporization?

Answer 14

It is the phase change from liquid to gas.

Question 15

What is condensation?

Answer 15

It is the phase change from gas to liquid.

Question 16

What is freezing?

Answer 16

It is the phase change from liquid to solid.

Question 17

What is sublimation?

Answer 17

It is the phase change from solid to gas.

Question 18

What is deposition?

Answer 18

It is the phase change from gas to solid.

Question 19

What is critical temperature?

Answer 19

It is the highest temperature at which a distinct liquid phase can form.

Question 20

What is critical pressure?

Answer 20

It is the pressure required to bring about liquefication at this critical temperature.

Question 21

What is a supercritical fluid?

Answer 21

It is when the temperature exceeds the critical temperature and the pressure exceeds the critical pressure, and the liquid and gas phases are indistinguishable from one another. It expands to fill its container like a gas, but the molecules are still tightly spaced like a liquid.

Question 22

What is vapor pressure?

Answer 22

It is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature in a closed system.

Question 23

What is dynamic equilibrium?

Answer 23

The condition in which two opposing processes occur simultaneously at equal rates.

Question 24

What does it mean when a liquid is volatile?

Answer 24

It means it will evaporate readily.

Question 25

What is a boiling point of a liquid?

Answer 25

It is the temperature at which its vapor pressure equals the external pressure, acting on the liquid surface.

Question 26

What is the normal boiling point of a liquid?

Answer 26

It is the boiling point of a liquid at 1 ATM.

Question 27

What is a phase diagram?

Answer 27

It is a graphic way to summarize the conditions under which equilibria exist between the different states of matter.

Question 28

What is a normal melting point?

Answer 28

The melting point at 1 ATM of a substance.

Question 29

What is a triple point?

Answer 29

The point at which all 3 phases (solid, liquid, and gas) are in equilibrium.

Question 30

What is a liquid crystal?

Answer 30

It is the viscous, milky state that some substances exhibit between the liquid and solid states.

Question 31

What is a nematic liquid crystal?

Answer 31

It is a crystal liquid in which the molecules are aligned so that their long axes tend to point in the same direction but the ends are not aligned with one another.

Question 32

What are smectic A and smectic C liquid crystals?

Answer 32

They are liquid crystals in which the molecules maintain the long-axis alignment seen in nematic crystals, but in addition they pack into layers.

Question 33

What is a cholestoric liquid crystal?

Answer 33

It is a liquid crystal in which the molecules are arranged in layers, with their long axes parallel to the other molecules within the same layer.

Question 34

Asymmetric molecular geometries are affected by what kind of Van der waals force (primarily)?

Answer 34

Dipole-dipole forces, which affect polar (asymmetric) bonds.

Question 35

Symmetric molecular geometries are affected only by what kind of Van der Waals force?

Answer 35

London dispersion forces