Chapter 2, Problem 56P

(E) Label each of the following as strong acid, strong base, or neither.

Several acids and their respective equilibrium constants are: Which is the strongest acid? Which is the weakest acid? Which acid has the weakest conjugate base? Which acid has the strongest conjugate base?

The following are equivalent ways of asking about the acidity of an H atom: • What is the most acidic H on the molecule? • Which H is associated with the published pKa value? • Which H on the molecule is easiest to remove? • Which H on the molecule takes the least energy to remove? • Which bond to an H is most polarized? • For which H atom is removal least uphill in energy? • Which bond to an H atom, when broken, results in the lowest PE conjugate base? We will often find the last of these questions is easiest to answer. To do this, find all the different Hatoms on the molecule, and draw all possible conjugate bases.Only the lowest-energy one is the “real” conjugate base. Identify this structure, and you have found the most acidic H. Use this strategy to find the most acidic H on each of the following molecules. Note: Each structure hasat least three different kinds of H’s, so draw at least three unique conjugate bases for each.

Summarize the relationship between pKa and base strength by completing the followingsentences: a. For a given base, the higher the pKa of its conjugate acid, the stronger or weaker the base. b. For a given base, the lower the pKa of its conjugate acid, the stronger or weaker the base.

The following reactions illustrate Brnsted acid-base behavior. Complete each equation. a.HI(aq)+?H3O+(aq)+I(aq) b.NH3(l)+?NH4++NH2 c.H2C2O4(aq)+H2O(l)?+HC2O4(aq) d.H2N2O2(aq)+H2O(l)H3O+(aq)+? e.?+H2O(l)H3O+(aq)+CO32(aq)

For each molecule below, draw the conjugate acid or conjugate base or both if the molecule hasboth a conjugate acid and a conjugate base (e.g., water).

Which is the stronger acid and which is the stronger base?

Which compound, M or N, is the stronger acid? Explain your choice.

Which is a stronger base, S2 - or Se2 -? Explain.