CHEM 202 chapter 11: intermolecular forces, liquids, and solids

Large intermolecular forces in a substance are manifested by __________.

low vapor pressure, high boiling point, high heats of fusion and vaporization, high critical temperatures and pressures 

Of the following, __________ is an exothermic process.

freezing

The vapor pressure of any substance at its normal boiling point is________________.

1atm or 760 mmHg

The property responsible for the "beading up" of water is __________.

surface tension

viscosity

the resistance to flow

How high a liquid will rise up a narrow tube as a result of capillary action depends on __________.

the magnitudes of cohesive forces in the liquid and adhesive forces between the liquid and the tube, and gravity

The shape of a liquid's meniscus is determined by __________.

the relative magnitudes of cohesive forces in the liquid and adhesive forces between the liquid and its container

characteristics of gas

assumes the volume and shape of container and has rapid diffusion

characteristic of liquid

takes the shape of container but not the volume of the container, readily and slow diffusion

characterisitc of solids

retains the shape of its container and has a definite volume, with very slow diffusion.

intermolecular forces

forces between molecules that determine the physical properties of substances, including boiling and melting points.

dipole-dipole force

attractive forces between polar molecules due to the positive end of one molecule being attracted to the negative end of another.

hydrogen bonding force

a strong type of dipole-dipole interaction that occurs between molecules containing hydrogen bonded to highly electronegative atoms like oxygen, nitrogen, or fluorine.

london dispersion force

a weak intermolecular force arising from temporary dipoles in nonpolar molecules.

ion-ion interactions

attractive forces between charged ions in an ionic compound, resulting from the electrostatic attraction between oppositely charged ions.

ion-dipole forces

interactions between an ion and a polar molecule, where the charge of the ion is attracted to the partial charges of the polar molecule.

viscosity

the resistance to flow which increases with stronger intermolecular forces and larger molecular size.

surface tension

the energy required to increase the surface area of a liquid, resulting from cohesive forces between liquid molecules.

capillary action

the ability of a liquid to flow in narrow spaces without the assistance of external forces, caused by adhesive and cohesive forces.

phase change

the transformation of the three states of matter (solid, liquid, gas) due to changes in temperature or pressure.

heat of vaporization

liquid to gas

heat of fussion

solid to liquid

sublimation

solid to gas

heating curve

used to illustrate phase changes and energy changes accompanying them

critical tempature

highest tempature at which substance can exist as a liquid

critical pressure

the pressure required for liquification of a gas at a critical temperature

dynamic equilibrium

rate of gas molecules condensing equaling rate of liquids evaporating

volatile liquids

liquids that evaporate easily

normal boiling point

1 atm or 760 mmHg

point T of phase change

triple point where all three states exist

Line TC of phase change

boiling point of the substance at that pressure

Point C of phase change

critical point where the highest tempature and pressure exist

Segment TA of phase change

The line represents the melting point of a solid at any given pressure

Segment of TB of phase change

sublimation point line which represents a solid and gase phase in equilibrium.

Which of the following is NOT a type of van der Waals force?

covalent bonding

Which type of intermolecular force is present in all molecular substances, regardless of polarity?

London Dispersion Forces

Which of the following substances exhibits hydrogen bonding?

NH3

What happens to the viscosity of a liquid as temperature increases?

decreases

Which of the following factors affects London Dispersion Forces?

Molecular size, Molecular shape, Electron cloud polarizability

Which of the following intermolecular forces is the strongest?

ion-ion interactions

Which of the following statements about hydrogen bonding is TRUE?

It occurs when hydrogen is bonded to N, O, or F.

Which of the following factors increases the strength of London dispersion forces?

increased molecular weight

Which of the following factors affects the viscosity of a liquid?

temperature, intermolecular forces, molecular size

What is the primary reason water exhibits a concave meniscus in a glass tube?

Strong adhesive forces

Which property of liquids is responsible for the formation of spherical droplets?

Surface tension

What happens to the surface tension of a liquid as temperature increases?

it decreases

What happens to the boiling point of a liquid when external pressure is decreased?

decreases

Which phase change occurs when a solid directly transforms into a gas

sublimation

Which of the following phase changes is exothermic

condensation

What is the name of the temperature at which the vapor pressure of a liquid equals atmospheric pressure

boiling point

What is the significance of a substance’s critical temperature?

It is the temperature at which a gas becomes a supercritical fluid

Which of the following statements is TRUE about phase diagrams?

The slope of the solid-liquid boundary in water's phase diagram is negative.

Which of the following molecules would exhibit hydrogen bonding?

NH₃ (Hydrogen bonding occurs when H is directly bonded to N, O, or F. NH₃ (ammonia) contains N-H bonds, allowing for hydrogen bonding.)