Five acid-base equilibria are shown below. In each equation the two reactants on the left side of the equilibrium are designated A & B; the two reactants on the right are designated C & D. In the first equation, the charges of ionic reactants are shown; for the other four reactions these charges are omitted. In the fifth equation, H₂CO₃ is reactant C and NH₃ is D. NaCl is an inert product. A table of pK_a values is provided at the bottom of the page.
For each equilibrium, three questions are posed:

• Which reactants function as Brønsted acids?   [Two letters (A through D) should be entered in the answer box.]
• Which reactant is the stronger base?   [One letter (A through D) should be entered in the answer box.]
• Which side of the equilibrium is favored?   [Two letters (AB or CD) should be entered in the answer box.]

Reactant A + Reactant B		Reactant C + Reactant D	Which act as acids?	Which is the stronger base?	Which side is favored?
(CH3)3COH   +   Na(+) OH(–)		(CH3)3CO(–) Na(+)   +   H2O	Enter two letters	Enter one letter	Enter two letters
HF     +     CH3CO2Na		NaF     +     CH3CO2H	Enter two letters	Enter one letter	Enter two letters
NaSH     +     C6H5OH		H2S     +     C6H5ONa	Enter two letters	Enter one letter	Enter two letters
NaCN     +     Na2HPO4		Na3PO4     +     HCN	Enter two letters	Enter one letter	Enter two letters
NaHCO3     +     NH4Cl		H2CO3   +   NH3   +   NaCl	Enter two letters	Enter one letter	Enter two letters

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Acid	HCl	H3O(+)	H3PO4	HF	CH3CO2H	H2CO3	H2S	NH4(+)	HCN	C6H5OH	H2O	(CH3)3COH	NH3
pKa	-7	-1.7	2.2 7.2 12.3	3.2	4.7	6.4 10.3	7.0	9.2	9.3	10.0	15.7	19	34