Structure, Bonding, Reactivity Flashcards
Stronger bond would have a higher or lower bond dissociation energy?
Higher because bond dissociation energy measures strength of chemical bond
Smaller atoms form shorter or longer bonds?
as atomic size decreases, the bond length to a neighboring atom decreases
Which one has weaker pi-bond, unsubstituted or substituted alkene?
Pi-bond is weakest in an unsubstituted alkene. Unsubstituted alkenes are less stable than substituted.
Lower heat of hydrogenation means that molecular is more or less stable?
lower heat of hydrogenation implies that the reactant molecule is more stable. The more stable compound, the stronger its pi-bond.
Is caffeine (double ring) planar?
Because of the delocalization of electron density throughout the pi-network of the caffeine
molecule (achieved by the resonance between all adjacent non-hydrogen atoms), the compound must be planar to allow the p-orbitals to overlap correctly.
Does resonance in a carbonyl cause longer or shorter C-O bond?
Longer bond because resonance can make the C-O bond have some single bond character.
The more s-character in a hybrid orbital, the shorter or longer bond?
Shorter bond
If compound is more polar, will it have a higher or lower boiling and melting point?
Higher because more intermolecular forces
What makes a good solvent?
A good solvent for dissolving a dye to form an ink is one that is a liquid at room temperature, evaporates quickly, and exhibits a high degree of dye solubility. If it has functional groups that are similar to the dye, then the dye is likely to be highly soluble in the solvent.
What makes a good soap?
Ionic/polar end and organic/nonpolar end with very long tails
What compounds dissolve most easily in water?
Polar/ionic and short molecules
sp2 hybridization has what type of geometry?
Trigonal planar
Where does protonation happen on amide?
Oxygen
Boiling point is…
vapor pressure equals atmospheric pressure
A higher vapor pressure at room temperature corresponds with a higher/lower boiling point?
Lower
Higher boiling points for more flexible or rigid molecule?
More flexible because more flexible ones can tangle together, so single bonds are more flexible than double bonds and should have a higher boiling and melting point than molecules with double bonds
Is boiling point lower or higher at higher elevations?
Higher elevations means lower atmospheric pressure and the lower atmospheric pressure means that less energy (heat) is required to reach a temperature at which the vapor pressure (Pvapor) is equal to the atmospheric pressure (Patmospheric) (the definition of the boiling point). The boiling point is therefore lowered as elevation increases.
Are optically active molecules polar or nonpolar?
All optically active compounds must be asymmetric in order to be optically active, so they must be at least slightly polar.
What happens to a micelle when it goes from aqueous to hydrophobic environment?
Micelle turns itself inside out so tails are pointing outward and heads are inside. This is the mechanism that enables water-insoluble drugs to be transported through the bloodstream, which is aqueous, to the lipid membranes of the body, which are hydrophobic
Purpose of micelle?
A micelle enhances the water solubility of a compound that is normally insoluble in water.
As hydrogen bond increases, what happens to the IR spectrum?
The IR signal broadens and maximum absorbance occurs at a lower wave number.
As hydrogen becomes more acidic, does the homolytic bond energy increase/decrease?
Increases because it is more difficult for hydrogen to remove one electron from the bond to carbon to make the split equal, so the energy required increases
If you increase s character then what happens to the bond and homolytic bond energy?
Increasing s character shortens the length of the bond, so it becomes stronger bond and the homolytic bond energy will increase as well.
When equilibrium constant is greater than 1.0, what is the relative concentration of the products and reactants?
Higher concentration of products compared to reactants
What does hydrogen bonding/protic solvent do to reaction rate?
The conclusion must be that hydrogen bonding decreases the reaction rate, due to hindrance of the nucleophile. Solvent can bind to nucleophile because both polar so the nucleophile attacks the electrophile less rapidly, there is competition basically
Is E or Z polar?
E is cis so it is polar always, but Z depends but usually since it is trans it would probably cancel out
What kind of compound, more stable or less stable, will release more heat upon combustion?
Less stable
