exam 2

Ion-Ion

intermolecular force between two Ionic molecules

ex. Na+Cl-

Ion-Dipole
ontermolecular force between ion & polar molecule
Dipole-Dipole
intermolecular forces between polar molecule & polar molecule

Dipole induced Dipole

 

intermolecular forces between polar molecule & non-polar molecule
London Forces

Exist for all species (polar or non-polar) but only become significant only when all other forces do not exist

 

The strength of london force depends upon the size (or molecular weight) of the species.

 

Bigger/Heavy=Stronger Force

Bond strength order from strongest to weakest.

1) H group bonds

2)dipole-dipole

3)London Forces

4) molercular weight

Vaporization of a liquid is dependant on what?

TEMPERATURE!

↑ liquid temp= ↑ vaporization rate

 

↑ surface area=↑ vaporization rate

 

↓ strength of intermolecular forces=↑ vaporization rate

 

ΔHvap in kJ/mole

 

 

Suppose for H2O @ 25°c is 44kJ/mole. how much heat is needed to vaporise 36mL of H2O?

 * What is being vaporised?

*mL→g

*g→mole

*mole→kJ

 

(36mLH2O)(1gH2O/1mLH2O)(1moleH2O/18gH2O)(44kJ/1mole)=88kJ

Hydrogen Bonds

sort of super dipole-dipole force. 

Hydrogen bonds strongly with F, O, and, N

Vapor pressure and dynamic equilibrium

when a system in dynamic equilibrium is disturbed, the system responds so as to minimize the disturbance and return to a state of equilibrium!

 

Dynamic equilibrium: Rate of evaporation=Rate of condensation

Simple cubic

[image]

 

8 corners

Faced center cubic

[image]

8 corners+ 6 faces

Body centered cubic

[image]

8 corners+ 1 body

What makes a good electrical conductor?

A) you must have charge… think ions

 

B) Ions must be free to move

WHy are metals good conductors?
they do not hold onto there electrons very strongly allowing them to move freely
ΔHsub
=ΔHfus+ΔHvap
molecular solid
ice
network covalent solid
diamond
t1/2
half life- the time required for the concentration of a reactant to fall to one half of its initial value.
enzyme
are biological catalysts thats increase the rates of biological reactions