[fogee7]

1 - In presence of an enzyme, at 298K hydrolysis of fructose-1-phosphate:
fructose-1-phposphate + H2O >>>>> fructose + Pi

leads to equilibrium state in which concentration of fructose-1-phposphate is 6.52 × 10^-5. Calculate ΔG0 ( Gibbs free energy ) for this reaction if initial concentration of fructose-1-phposphate was 0.2M


2 - For the chemical reaction A >>>>B the change of free energy follows the formula ΔG (kJ) = ΔG0 +
RT × ln[ B]/[A] and for the room temperature ΔG(kJ) = ΔG0 + 5.71 × log[ B]/[A].

[ B] and [A] represent molar concentrations of the product and reactant. Check if the isomerization reaction A >>>>> B is spontaneous at 25 C .For the B and A concentrations equal to 0.1M and 1mM respectively. Assume that ΔG0 = -5 kJ. Calculate the equilibrium constant (K). Tell what is the value of ΔG at equilibrium

3 - Concentration of inorganic phosphate inside cells is 10^-2M, ratio: [ATP]/[ADP] = 10.

Calculate ΔG’ for ATP hydrolysis : ATP + H2O >>> ADP + Pi for above concentrations and pH 7.0, temperature 25 C if ΔG0’ = - 32.18 kJ/mol. What is the direction of the spontaneous process in given conditions?

4 - Redox reactions could be performed in the galvanic cell where oxidation and reduction reactions proceed in the separate places (half-cells). Write the Nernst equations for the following half-cells:

Fe3+/Fe E0 = - 0.44 V,   Fe3+ + 2e >>>>>> Fe
Br2/Br- E0 = + 1.08 V ,   Br2 + 2e >>>>>2 Br-
O2/H2O E0 = + 1.23 V,   O2 + 4H+ +4e >>> H2O

Find out which reaction is proceeding in the standard condition in the cell (A) Fe/Fe3 // Br-/Pt(Br2), and nonstandard conditions in the cell (B) Pt(Br2) /Br- // H2O,H+ /Pt(O2).
Assume that in the cell B concentrations of reactants except H+ are equal 1M or are constant and pH of the solution is equal to 7.

In the cells A and B indicate the cathode and the
anode. Calculate the equilibrium constants (K) for the reaction proceeding in the galvanic cell A
and B. Which reaction is practically irreversible?


5 - Numerous oxidation reactions in the living systems are in fact the dehydrogenation ones and proceed according to the scheme AH2 >>>>> A + 2H+ + 2e. For this type of reactions the biological standard potential (E0’) is defined as a standard potential at pH 7.

Write down Nernst equations the “chemical” and biological potential of the reaction.
NADH2/NAD+ E0 = - 0.315 V, NADH2 >>>NAD+ + 2H+ +2e


A hint: The relation between E0’and E0 find from the relation: E = E0 + 0.059/2 × log[H+] + 0.059/2 × log[NAD+/NADH2] for pH 7. Brackets represent molar concentrations.

6 - For the following reactions:
pyruvate + 2H+ + 2e >>>>>>>>> lactate Eo’ = - 0.19 V

NAD+ + 2H+ + 2e >>>>>> NADH + H+ Eo’ = - 0.32V

Write the spontaneous net cell reaction which will occur:
a) under standard conditions
b) for [NAD+]/ [NADH + H+] = 1000 and [lactate]/[pyruvate] = 1000 at 25°C.

7 - Four experiments were performed. Initial concentrations of reactant (A, B ) and the rate (v) of the reaction were measured (table): A + B >>>>>> AB

No 1 [A] = 0.1 (M) , [ B] (M) = 0.1 , v sec-1 = 10^-3

No 2 [A] = 0.01 (M) , [ B] (M) = 0.1 , v sec-1 = 10^-4

No 3 [A] = 0.1 (M) , [ B] (M) =0.01 , v sec-1 = 10^-3

No 4 [A] = 0.01 (M) , [ B] (M) = 0.01 , v sec-1 = 10^-4







Tell the overall order of the reaction and write the rate law. Calculate the kinetic constant (k), a half-life (t1/2) and the concentration of AB after 10 sec of the reaction course. Initial concentration of A was 10-2M.


* Assuming that in the one step only two molecules can collide suggest the possible mechanism of this process. Is it the one or two-step process?

8 - Apply the Arrhenius equation to calculate how many times the rate of the catalyzed reaction is increased when the activation energy is decreased from 50 kJ (unanalyzed reaction) to 20 kJ (catalyzed reaction) at the presence of catalyst. Assume that temperature for both processes is 298K and other constants from Arrhenius equation are identical. Explain why the reaction rate of the one step process is increased when temperature is elevated.


HELP PLEEEEEEEEEEESE !!!

[sjb]

1 - In presence of an enzyme, at 298K hydrolysis of fructose-1-phosphate:
fructose-1-phposphate + H2O >>>>> fructose + Pi

leads to equilibrium state in which concentration of fructose-1-phposphate is 6.52 × 10^-5. Calculate ΔG0 ( Gibbs free energy ) for this reaction if initial concentration of fructose-1-phposphate was 0.2M

What are your thoughts? Also, please pay attention to formatting (see e.g. http://www.chemicalforums.com/index.php?topic=59314.0). Unfortunately, the way you have written the concentration of B is the same as the forum code for emboldening text.

[Borek]

What are your thoughts? Also, please pay attention to formatting (see e.g. http://www.chemicalforums.com/index.php?topic=59314.0). Unfortunately, the way you have written the concentration of B is the same as the forum code for emboldening text.

Corrected that.