Experiment 25 Advance Study Assignment: pH Measurements-Buffers and Their Properties 1. A solution of a weak acid was tested with the indicators used in this experiment. The colors observed were as follows: Methyl violet Thymol blue Methyl yellow violet yellow Congo red Bromocresol green orange-red blue-green yellow What is the approximate pH of the solution? 2. The ammonia (NH3) molecule is the conjugate base of the NH4+ (called ammonium) ion, a weak acid. An aqueous solution of NH3 has a pH of 11.6. Write the net ionic equation for the reaction that makes an aqueous solution of NH3 basic. (The answer looks very similar to Eq. 5 in the introduction to this experiment.) 3. The pH of a 0.010 M HOBI solution is 5.3. a. What is [H+] in that solution? b. What is [OBr]? What is [HOBr]? (Where do the H+ and OBr ions come from?) C. What is the value of K for HOBr? What is the value of pK? M; M (continued on following page) M 3.