CHE 002B: Liquids and Solids

Ideal Gas

high temp + low pressure

Surface Tension

the resistance to an external force due to molecular attractions

• decreases with high temp

Cohesive Forces

forces between like molecules

Adhesive Forces

forces between unlike molecules

Capillary Action

strong adhesive forces which allow a liquid to be drawn up a tube

Viscosity

resistance to flow of a liquid; a result of cohesive forces

Vaporization

molecules go from liquid to gas state

• high temp, high surface area

Vapor Pressure

partial pressure of the gas directly above the liquid

Vapor Pressure is ___ atmospheric pressure

less than

Enthalpy of Vaporization H(vap)

• measures evaporation

• endothermic process (+)

Condensation

• exothermic process (-)

Boiling Point

VP = P atm

At _____, boiling occurs at ____ temp

1. high elevation

2. lower

Critical Point

liquid and vapor become indistinguishable

Triple Point

all three phases coexist

Clausius-Clapeyron Equation

ln(p2/p1) = HVAP/R (1/T1 - 1/T2)

The ______ displays ____ above a solid as a function of Temp and ______ as a function of external pressure

1. sublimation curve

2. sublimation point

Vapor Curve and Vapor Pressure Curve display ____

1. liquid as a function of Temp

2. BP as a function of external pressure

Water has a _____ slope of ____ curve due to the density of liquid water being higher than solid ice

1. negative

2. fusion

Heating Curve

a function of temperature due to heat added

Types of Crystalline Solids

1. Metallic

2. Ionic

3. Molecular

4. Network Covalent

Molecular Solids

• weak interactions

• soft + low mp

Ionic Solid

hard + high mp

Network Covalent

hard + high mp

Nonpolar

• london dispersion

• soft + low mp

Polar

• dipole-dipole

• low mp

Hydrogen Bond

low mp

Types of Forces: High to Low

1. Ion-Ion

2. Hydrogen

3. Dipole-Dipole

4. London Dispersion

London dispersion forces depend on ______

molecular size

Ion-Ion Interactions

increase with increasing ion charge and decreasing ionic size

Dipole-Dipole

polar molecules that have permanent dipoles align to yield attractive D-D interactions

The more _____, the higher the ____

1. polar

2. boiling point

Dipole

electrons are shared unequally between atoms

Instantaneous Dipole/Induced

a temporary dipole produced when electrons are more concentrated in one area of an atom

London Dispersion Forces

short-ranged attractions between instantaneous + induced dipoles

The greater the molecular mass, the greater the _______

london dispersion forces

When do h-bonds form?

1. directly bonded to EN elements: N, O, F

2. occur between H of one molecule + En element of the other

Strong LDF

Long and skinny molecule

Weak LDF

short and fat molecule

Boiling Point ____ with molecular mass and polarity

increases

Boiling Point: High to Low

1. H-Bond + London

2. Polar: D-D + London

3. Nonpolar