27. Given the following acid dissociation constants,
Ka (H3PO4) = 7.5 x 10–3
Ka (NH4+) = 5.6 x 10–10
determine the equilibrium constant for the reaction below at 25 ºC.
H3PO4(aq) + NH3(aq)    NH4+(aq) + H2PO4-(aq)

a. 4.2 x 10–12
b. 7.5 x 10–8
c. 4.2 x 102
d. 1.3 x 107
e. 2.4 x 1011

Answer: _____


30. When a Lewis acid combines with a Lewis base, the base supplies both electrons to the bond. This type of chemical bond is called a(n) ________ covalent bond.