Quiz 2 - Intermolecular Forces Flashcards
Intermolecular Forces are attractive forces _________ molecules.
Between
Intramolecular Forces are forces _________ ________ _________ in a molecule.
Holding atoms together
How many kcal does it take to vaporize 1 mole of water using INTERmolecular Forces?
10 kcal
How many kcal does it take to vaporize 1 mole of O-H bonds in water using INTRAmolecular Forces?
110 kcal
Generally Intermolecular Forces are much __________ than Intramolecular forces.
WEAKER
Intramolecular Forces are mainly ______.
Bonds
What are different ways of measuring Intermolecular Forces?
- Boiling Point
- Melting Point
- ΔHvap
- ΔHfus
- ΔHsub
What are the 2 things that generate Intermolecular Forces?
I) Partial Charge
II) Charge Interactions
Formal Charges = …
Stronger Interactions
Partial Charges = …
Weaker Interactions
What is an example of a Ion-Dipole Interaction?
The hydration of Sodium and Chloride ions in water
Ex. Ion-Dipole Interaction (Sodium & Chloride ions in H2O)
Waters behave as _________ surrounding a central _________ or _________ _____.
Ligands; metal; halogen ion
What are the weak Intermolecular Forces?
- Dipole-Dipole
- Dipole-Induced Dipole
- Instantaneous Dipole-Induced Dipole (London Forces)
Weak Intermolecular Forces are also called…
Van der Waals Forces
Boiling points for non-polar molecules that are considered London Forces have boiling points that increase when…
The more electronegative molecule has a lower boiling point, whereas a less electronegative molecule has a higher boiling point
__________ species give rise to London Dispersion Forces.
Polarizable
London Dispersion Interactions operate in all molecules but are the only ___________ ____________ that occur between ___________ molecules.
Intermolecular Interactions; non-polar
London Forces are also called…
Instantaneous Dipole-Induced Dipole Interactions
London Forces are interactions resulting when a molecule establishes an __________ _________ as a result of ________ __________ produced in a molecule based of _________ _________ _________.
Instantaneous dipole; charge separation; random electron motion
What happens when a London Force molecule gets near another molecule?
When this molecule is near another molecule it can induce a dipole in the 2nd molecule
The arrangement of the dipoles in London Forces will produce an…
Attractive Interaction (+/-)
The larger the molecules, the _________ the number of electrons that can be involved in dispersion interactions.
GREATER
Generally, as the molecular weight increases the strength of London Dispersion Forces _________.
INCREASES
_________ _________ is important in determining the magnitude of London Dispersion Forces.
Molecular Shape
Explain London Dispersion Forces in a fairly spherical shape
There is less surface area for dispersion forces to operate when the molecules are in contact
Explain London Dispersion Forces in an extended structure
Extended structure allows for more contact points for dispersion forces to operate
For Hydrogen Bonding to occur, H must be on an __________ _______ such as ___, ___ or ___.
Electronegative atom; O; N or F
For Hydrogen Bonding to occur you need a __________ Bond.
Hydrogen
For Hydrogen Bonding to occur, the other terminus of the hydrogen bond must be an __________ ________ such as ___, ___ or ___.
Electronegative atom; O: N or F
Hydrogen Bonds are very ____________.
Directional
Hydrogen Bonds align along ______ _______ and ___________ ______.
X-H bonds; non-bonded pairs
Hydrogen Bonds are typically _________ than other dipole-dipole attractions.
STRONGER
Why are Hydrogen Bonds typically stronger?
Because the small size of H allows less distances between the charges
How to determine the H of Hydrogen Bond Donors?
Look for the H’s on the O’s (alcohols/acids) or N’s (amines/amides) to account for the # of HBDs
How to determine the H of Hydrogen Bond Acceptors?
THe # of non-bonded pairs on the N’s and O’s which can interact with HBD’s
How do Non-Bonded Lone Pairs affect Hydrogen Bond Acceptors?
Non-bonded lone pairs participate in resonance so they make Hydrogen Bond Acceptor’s availability almost 0
Are Non-Bonded Lone Pairs counted as Hydrogen Bond Acceptor sites?
No they are not
If you have a primary amide or aniline, the lone pair on the amide “N” _____ participate in hydrogen bonding.
CAN
Lone pairs on “N” on amides attached to aromatic rings are _____ likely to hydrogen bond.
Less
Why do lone pairs on “N” on amides attached to aromatic rings have a lesser likelihood of hydrogen bonding?
Because there is significantly greater interaction between the amide functional group and the aromatic ring
Polar compounds dissolve in _________ solvents.
Polar
Non-polar compounds dissolve in ___________ solvents.
Non-polar
Solubility depends on ___________ ___________ between polar surfaces or non-polar surfaces, both of ________ and __________.
Complementary interactions; solvent; solute
NaCl dissolves in _________.
Water
NaCl does not dissolve in _____________.
CH3(CH2)3CH3
T/F CH3(CH2)3CH3 and water mix well and do not form layers
False; they do not mix with each other and they form 2 layers
CH3OH through CH3CH2CH2OH = …
Mixes with water in all proportions
CH3CH2CH2CH2OH = …
Slightly soluble in water
CH3CH2CH2CH2CH2OH = …
Essentially insoluble
What is the 4 1/2 Carbon Rule?
Rule that exemplifies the big transition in solubility between 4C and 5C compounds
