Question

A weak acid (HA) reacts with a weak base (B) to form the conjugate base of the acid (A-) and the conjugate acid of the base (B-H+). If the pKa of HA was 4.7 and the pKa of BH+ (i.e., the pKabH of B) was 9.4, what would be the value of the equilibrium constant for the above reaction to the nearest ones? Obviously, by expressing the answer to the nearest ones, we are using too many figures than is warranted, but this is necessary because Canvas is not configured to use scientific notation.

The pure D-form of a compound has a specific rotation (D line of sodium, 20° C) of +25°, whereas the pure L-form of the compound has a specific rotation (D line of sodium, 20° C) of -25°. If a scientist has a sample of this compound that is known to be 80% pure D-form (and, therefore, 100% - 80% pure L-form), what will be the observed rotation of this sample? Enter your answer to the nearest hundredth. The units are assumed to be degrees.