Chapter 11 --> Liquids, solids, and intermolecular forces

Describe dispersion forces.

temporary polarity in molecules due to unequal electron distribution

Describe dipole-dipole attractions.

permanent polarity in the molecules due to their structure

Describe hydrogen bonds.

an especially strong dipole-dipole attractions results when H is attached to an extremely electronegative atom

What are the factors that effect dispersion forces?

molecular size and molecular shape

Describe dipole-dipole interaction.

Positive end of a polar molecule is attracted to the negative end of its neighbor

Describe dipole moment and boiling point.

higher boiling point = higher dipole moment

what does solubility depend on?

attractive forces of solute and solvent molecules

what do polar molecules dissolve in?

polar solvents; hydrophobic groups

what do nonpolar molecules dissolve in?

nonpolar solvents

how does H bonding impact attractive forces?

when H bonds to F, O, or N atoms require large partial charges giving strong dipole-dipole attractions

what is the effect of hydrogen bonding on boiling point?

greater hydrogen bonding = greater boiling point

what is one of the main factors that determines solubility of ionic compounds in water?

strength of ion-dipole attractions

describe surface tension.

tendency of liquids to minimize surface area

how do liquids minimize surface area?

by forming spherical drops

what makes higher surface tension?

stronger intermolecular forces

what does raising temperature do to its surface tension?

reduces it; increases average kinetic energy making it easier to stretch the surface

what is viscosity?

the resistance of a liquid to flow

larger IMF forces = ____________ viscocity

greater

more spherical IMF forces = ___________ viscocity

lower

describe adhesive forces.

pull surface liquid up side of the tube

describe cohesive forces.

pull interior liquid with it

a __________ tube diameter, the __________ the liquid will rise

narrower; higher

describe meniscus.

the curving of the liquid surface in a thin tube is due to competition between adhesive and cohesive forces

describe vaporization

if high energy molecules are at the surface they may have enough energy to overcome the attractive forces; this will allow them to escape the liquid and become a vapor

larger surface area = __________ rate of evaporation

faster

describe condensation.

some molecules of the vapor will lose energy through molecular collisions and get captured back into the liquid

the __________ the attractive forces among molecules, the ______ energy they will need to vaporize and will evaporate quicker

weaker; less

liquids that evaporate quickly are _____________

volatile

give examples of volatile substances

gasoline, nail polish remover

liquids that do not evaporate quickly are ____________

nonvolatile

gives examples of nonvolatile liquids

motor oil

describe heat of vaporization (deltaHvap)

amount of heat energy required to vaporize one mole of liquid; always endothermic and somewhat temperature dependent

describe vapor pressure.

pressure exerted by a vapor when its in dynamic equilibrium with its liquid

the ____________ the attractive forces among molecules, the _____________ molecules will be in the vapor; inverse relationship

weaker; more

the ____________ the vapor pressure the more volatile the liquid

higher

describe boiling

when temperature of a liquid reaches a point where its vapor pressure is the same as the external pressure

describe boiling point

when vapor pressure equals external pressure

normal boiling point is the temperature when vapor pressure is = __________

1 atm

the __________ the external pressure the _______________ the boiling point of the liquid

lower; lower

as you heat a liquid its temperature increases ____________ until it reaches ______________

linearly; boiling point

what is the heat equation?

q = mass x cs x deltaT

once temperature reaches boiling point all the added heat goes to _______________; temperature remains ___________

boiling the liquid; constant

once all the liquid has been turned to gas the ____________ can rise again

temperature

what is the clausius-clapeyron equation?

m = -deltaHvap / R

What is the clausis-claperyron equation (two point form)?

ln(P1/P2) = -DeltaHvap/R(1/T1-1/T2)

what is the downfall of the two point form?

gives less precise results

what is a supercritical fluid?

have properties of both liquid and gas states

as you heat a solid its temperature increases ______________ until it reaches _________________

linearly; melting point

once the temperature reaches the melting point, all the heat goes into ________________

melting the solid

once all the solid has been turned into ____________, the temperature can ______________

liquid; rise

what is the heat of fusion?

amount of heat energy required to melt one mole of the solid; is always endothermic

what is the heat of fusion equation?

deltaHsublimation = deltaHfusion +deltaHvaporization

describe phase diagrams.

different states and state changes that occur at various temperature/pressure conditions

regions represent ______

states

lines represent _________

state changes

the liquid/gas line is the ____________________

vapor pressure curve

what is the critical point?

the farthest point on the vapor pressure curve

what is the triple point?

the temperature/pressure condition where three states exist simultaneously

the freezing point ___________ as pressure ____________________

increases; increases

changing from solid to liquid is the _________________

fusion curve

changing from solid to gas is the __________________

sublimation curve

water is a ________ at room temperature. What is this due to?

liquid; H-bonding between molecules

why is water an extraordinary solvent?

dissolves many polar and ionic molecular substances due to its large dipole moment

water has a very high ________________

specific heat

water ____________ when it freezes at a pressure of __________ atm.

expands; 1

the hydrogen bonds present in water result in a relatively _________ boiling point

high