Question

Part A The equilibrium constant Kn for the neutralization of boric acid (H3BO3) and caffeine (C8H10N4O2) is 24. What is Kb for caffeine? (Ka of boric acid is 5.8⋅10−10).

Answer 1

The equation for the neutralization reaction of boric acid and caffeine is Since boric acid is a weak acid (K, -5.8x10-0) and caffeine is a weak base, so equilibrium constant K for this reaction is expressed as It can be also written as

Now substitute the known values in this K expression, we get -(24)x1.0x104)x 5.8x100 =4.1x10-4 Therefore, the value of K, for caffeine is 4.1x101