BackWhich of the following parameters would be different for a reaction carried out in the presence of a catalyst compared with the same reaction carried out in the absence of a catalyst?
∆G°, ∆H‡, Ea, ∆S‡, ∆H°, Keq, ∆G‡, ∆S°, k
The following reaction has a value of ΔG° = –2.1 kJ/mol (–0.50 kcal/mol).
CH3Br + H2S ⇌ CH3SH + HBr
a. Calculate Keq at room temperature (25 °C) for this reaction as written.
Explain why the half-life (the time it takes for one-half of the compound to be metabolized) of Xylocaine is longer than that of Novocaine.
For each of the following acid–base reactions, (iii) calculate ∆G°. If a pKa is not one of the ten common ones we learned in Chapter 4, it will be given to you.
(a)
Calculate ∆G°, ∆H°, and ∆S° for the following acid–base reactions. Rationalize the value of ∆H° based on the structure of the conjugate bases. [Assume T = 298 K.]
(c)
For the following equilibrium processes and the corresponding ∆G° , indicate whether you expect the equilibrium constant to be greater than, equal to, or less than 1. Justify your expectation in words.
(b)
a. Which reaction has a greater equilibrium constant: one with a rate constant of 1 × 10-3 sec-1 for the forward reaction and a rate constant of 1 × 10-5 sec-1 for the reverse reaction, or one with a rate constant of 1 × 10-2 sec-1 for the forward reaction and a rate constant of 1 × 10-3 sec-1 for the reverse reaction?
b. If both reactions start with a reactant concentration of 1.0 M, which reaction will form the most product when the reactions have reached equilibrium?
Compounds containing deuterium (D = 2H) are useful for kinetic studies and metabolic studies with new pharmaceuticals. One way to introduce deuterium is by using the reagent LiAlD4, equivalent in reactivity to LiAlH4. Show how to make these deuterium-labeled compounds, using LiAlD4 and D2O as your sources of deuterium, and any non-deuterated starting materials you wish.
a. CH3CHDOH
In a reaction in which reactant A is in equilibrium with product B at 25 °C, what relative amounts of A and B are present at equilibrium if ∆G° at 25 °C is
c. -2.72 kcal/mol?
d. -0.65 kcal/mol?
For the following acid–base reaction, (d) calculate ∆G° at 298 K.