A few Midterm practice problems…
- Find
the pH, [H3O+], [OH-], and pOH for a:
- 0 .050M KOH solution.
- 0.030M
HCl solution.
- A
Lineweaver-Burk plot gave a slope of 0.0561 and
a y-intercept of 0.387.
- Calculate
Vmax for this reaction
- Calculate
KM for this reaction.
- If
the enzyme concentration used was 10-6M, use your calculated Vmax to determine the enzyme turnover
number.
- The
pKa’s for aspartic acid are 2.09, 3.86
(side chain), and 9.82.
- For
a pH of 3.0 draw the Lewis structures of the two most concentrated forms of
aspartic acid. Show all atoms,
bonds, charges, and lone pairs.
- For
a pH of 3.0, determine the relative fractions of the two most
concentrated forms.
- Explain
the difference in the overage charges for an aspartic acid ion when it is
in the stomach at a pH-1.5 vs being in a cell
at a physiological pH of 7.4. Fully support your answer.
- Alkaloids
are N-containing organic compounds that occur in nature. Research by students in the chemistry
labs at Winthrop
is currently demonstrating a new synthetic route to make nicotine (which
is an alkaloid) through a pathway that has never been done before.
- To
extract nicotine from ground tobacco into an aqueous solution, predict
whether it would be preferable to use an acidic or basic aqueous
solution. Use Henderson-Hasselbalch,
solubility, and your knowledge of nitrogen-containing compounds to
develop and to support your prediction.
- Once
nicotine has been extracted into an aqueous solution, predict how the pH
should be adjusted to get the nicotine to partition into the organic
layer of the organic solvent added to the solution. Fully explain and
support your prediction.
- Compare
the log P’s for 1-butanol, 1-decanol, glycerol, water, and pentane.
- Indinavir is a potent inhibitor of
the HIV-1 protease, and is used in the treatment of AIDS. It has a log P value of 2.7. 5.00 mL of
1-octanol was vigorously mixed with 200.0 mL of
water and 1 mmole of Indinavir
was added during mixing. Calculate the number of mmoles
of Indinavir that partition to each of the two
phases in the mixture.
- The
rate constant for the decomposition of HI at 573K is 2.91 x 10-6M/sec. The rate constant for this reaction at
673K is 8.38 x 10-4M/sec.
- Determine
the activation energy for this reaction in units of kJ/mole.
- For
a temperature of 573K, use your answer for the activation energy to
predict the fraction of collisions with sufficient energy to react.
- For
a temperature of 573K, determine the collision frequency factor.
- Draw
the mechanism and clearly show what occurs when ethanol reacts with ethanoic acid. Draw the structures of all reactants
and products.