The amino acid histidine has ionizable groups with PK, values of 1.8, 6.0, and 9.2, as shown. COOH COO COO HN-CH HN-CH H,N-CH 8-3-6) CH, H CH, H N N H N HN-CH CHH 9.2 PK, g-3-3-U=VI CH 1.8 PK, CH 6.0 pk, CH CH H C H N N H COOH COO lonizable group -NH --NH, -HisH+ = His A biochemist makes up 80 mL of a 0.13 M solution of histidine at a pH of 5.6. She then adds 60 mL of 0.10 M HCl. What is the pH of the resulting solution