General Lab stuff Flashcards
How do you know when something will ionize?
if pKa>pH-> acid form (protonated)
if pKa basic form (deprotonated)
When will something be present in a certain layer in extractions?
Organic layer: neutral compound
aqueous: Ions+charged compounds
How do you choose the correct NMR solvent?
How do you remove water from an extraction?
Using brine or Na2SO4
How do you know if there are halogens present in an MS?
If we have an M+2 peak, there is a halogen. If the M;M+2 is 3:1, then we have a Cl
if the M:M+2 is 1:1, then we have a Br
How do you know if there are Oxygens present in an MS? How do you know if there is Nitrogens?
For oxygens: Figure out the number of carbons first, then subtract the amount of possible oxygens from the remainder.
For nitrogens: If the M peak is even, we do not have a N.
What does a more negative Gibbs free energy signify?
A more negative Gibbs free energy means that a thing is more spontaneous, and is product favored at a lower energy.
What does a more negative dH formation signify?
This signifies that a molecule is more stable, and exothermic.
Why might Hydrogen peaks be missing from an NMR spectrum?
Hydrogen bonding with solvent, Deuterium makes peaks disappear
Why are O-H shifts variable on webMO?
Because they can interact with the solvent.
How can we determine spontaneity given the free energy of reactants/products?
If the free energy is negative, the molecule is spontaneous. However, we must compare the relative energies of the reactant and products because if they are too similar, the reaction will not be spontaneous.
Degree of Unsaturation
(2(C)+2-H+N+X)/2
benzene has 4 degrees of unsaturation
