Bonding & Reactions

Question 1

Strength of an acid

Answer 1

Almost entirely dependent on its ability to stabilize the resulting negative charge after deprotonation
Resonance does not contribute, but the size of the atom or molecule does (the larger the better the acid)

Question 2

Build-up of AMP in a cell would most likely:

Answer 2

AMP as a product, would then shift the equilibrium to the left; since activation of fatty acids is needed for triacylglycerol synthesis, decreased fatty acid activation will decrease the rate of triacylglycerol synthesis

Question 3

Double bonds overlap to form

Answer 3

Pi bonds, from two sp2 orbitals combining (overlap of perpendicular p orbitals)

Question 4

pH =

Answer 4

pKa + log ([A-]/[HA])
Example: pH = 6.35 + log (2) = ~6.7
* 2 is used for twice as much*

Question 5

Second ionization energy

Answer 5

The 2nd ionization energy of sodium is likely to be much, much larger than the first ionization energy, since the second electron is removed from a full subshell

Question 6

Structural changes that decrease polarity

Answer 6

• Replacing C=O with C=CH2
• Replacing N-Cn=N with CH-CH=CH
• Replacing NH with NCH3 (removes a hydrogen bond donor, thus decreasing water solubility)

Question 7

Structural changes that increase polarity

Answer 7

• Replacing benzene CH with N in the ring (now there would be a lone pair that could accept a hydrogen bond from water, thus increasing the solubility of the compound)

Question 8

Na+-NQR

Answer 8

Catalyzes two-electron reduction of a ketone to an alcohol
RC(=O)R –> RCH(OH)R

Question 9

Phosphatase

Answer 9

Catalyzes RO(PO3)^2- –> ROH + Pi

Question 10

Protease or amidase

Answer 10

Catalyzes RC(=O)NHR’ –> RCOOH + R’NH2

Question 11

Esterase

Answer 11

RC(=O)OR’ –> RCOOH + R’OH

Question 12

Nonpolar molecules

Answer 12

• CCl4 (while each C-Cl bond in carbon tetrachloride is polar, the sum of the dipole moments cancel as a result of its tetrahedral geometry)
• CO2 (linear molecule; the bond dipole moments of each C=O bond cancel as they are in opposite directions
• Li2 (necessarily nonpolar as it is comprised of two identical atoms)

Question 13

Polar molecule

Answer 13

• NF3 (the geometry of trifluoroamine is impacted by the lone pair on nitrogen, making it trigonal planar; no bond dipoles cancel, this results in a polar molecule)

Question 14

A major obstacle to obtaining useful energy from a nuclear fusion reactor is containment of the fuel at very high temps required for fusion; the reason such high temps are required is to:

Answer 14

• Enable reactants to approach within range of the strong nuclear force