CHEM 161 EXAM 1!

Gas

high KE, attractive forces < KE; no fixed shape or volume, particles far

Liquid

attractive forces>KE, lower KE; changes shapes, fixed volume, particles close

Solid

KE is low, attractive forces dominate; particles/volume/shape fixed

Vander Waals

the bonding force within the mole is intramolecular force

Phase Changes: Endothermic

solid→liquid= melting, liquid→gas=vaporizing, and solid→gas= sublimation

Phase Changes:Exothermic

gas→liquid= condensation, liquid→solid= freezing, gas→solid= deposition

Equation for Quantitative Aspects of phase Changes for stages 1,3,5

q=nc^T

Equation for Quantitative Aspects of phase Changes for stages 1 and 2

q=n times delta H, (endothermic add negative)

Vapor Pressure

is the pressure exerted by the vapor on the liquid, at equilbrium the pressure is constant.

Factors that affect vapor pressure

as temperatures increase, so does KE, vapor pressure increase

Weaker intermolecular forces

more easily particles enter the vapor phase, and the higher the vapor pressure

Vapor pressure _______ as temperature increases. Vapor pressure ____________ as the strength of the intermolecular forces _______________.

increases, increases, decreases

Clasius Clapeyron Equation

In P2/P1= - delta H/R x(1/T2-1/T1) R=8.134J/Mol ºK

Boiling point

when the vapor pressure equals external pressure

Melting point

melting rate←→ freezing rate

Triple point

all three phases are equilbrium

critical point

2 densities become equal and phase bounding disappears

Properties of liquids: surface tension

energy required to increase a liquid surface area. Greater intermolecular forces=higher surface tension

Properties of liquids: capillary action

the rising of liquid through a narrow space. Occurs when forces between a liquid and a surface are greater than those in the liquid

Properties of liquids: viscosity

the resistance of a fluid to flow.

Factor of Viscosity: increasing temp

decreases viscosity, because of higher KE

Factor of Viscosity: effect of molecular shape

example:which moves faster marbles falling out of jar or spagetti

Uniqueness of Water- shape

bent molecular shape, polar molecule with h-bonding

Uniqueness of Water- properties

water can dissolve many ionic and polar compounds

Uniqueness of Water- hydrogen bonding

is responsible for water’s high surface tension and high capillarity. Water has the highest surface tension of any liquid minus molten metals and salts

Unit cells

smallest portion that gives the crystal its properties if it is repeated in all directions

coordination number

the number of nearest neighbors of a particle

simple cubic unit cell

1/8 × 8= 1 atom, coor 6

body centered cubic unit cell

4r/ square root 3, 2 atoms

Face centered cubic unit cell

square root of 8 times r

A _________ dissolves in a solvent to form a solution

solute

Sometimes soultions are miscible with each other (soluble in any proportion) so the terms ___________ and _________ lose their meaning

solute and solvent

Solute may dissolve in another solvent if?

likes dissolve likes

Solubility of Solute

maximum amount that dissolves in a fixed quanity of solution at a given temperature.

Substances with similar intermolecular forces dissolve what?

each other

A solution is Homogenous when a mixture does what?

mixture of a solute dissolved in a solvent via intermolecular forces

h-bonding

attractive interaction between polar molecules including hydrogen

dipole dipole

absence of h-bonding, allows for polar molecules to dissolve polar molecules

Ion induced dipole forces

charge-induced dipole (polarizability). Ion’s charge distorts the electron cloud of a nearby non-polar molecule.

dipole induced dipole

polar molecule distorts the electron cloud of a nonpolar molecule. This force is weaker than ion-induced force.

Dispersion forces

this force contributes to the solubility of all solutes in all solvents. But it is the main force in non polar solutions

Solubility in Water

small alcohol solubility is high, large alcohol solubility is low

Solubility in hexane

small alcohol solubility is low, large alcohol solubility is high