2. Phosphoric acid (H3PO4) is a triprotic acid with the following pKa values: pKa1 = 2.15 pKa2 = 7.20 pKa3 = 12.35
a). You wish to prepare a 1.000 L of a 0.0450 M phosphate buffer at pH 6.8. Which of the following salts do you use (PICK 2) and what mass of each salt will you add to the mixture? H3PO4 (M.W.= 97.995) KH2PO4 (M.W.=136.086) Na2HPO4 (M.W.=141.959) AlPO4 (M.W.=121.953) 2
b). A concentrated phosphate buffer known as âphosphate buffered salineâ (or PBS) is made with the salts you choose from above in addition to NaCl and KCl. The 10x concentrated solution has a pH ~6.8 and the 1x concentrated (i.e., diluted with water) solution is ~7.1. Why?
c). You accidently grabbed the 10x concentrated phosphate buffered saline (or 10xPBS) instead of the 1xPBS solution and start to adjust the pH of your buffer with NaOH to reach your desired buffer pH. You notice it is taking much more base than with your usual 1xPBS buffer. Why?
2. Phosphoric acid (H3PO4) is a triprotic acid with the following pKa values: pKa1 = 2.15 pKa2 = 7.20 pKa3 = 12.35
a). You wish to prepare a 1.000 L of a 0.0450 M phosphate buffer at pH 6.8. Which of the following salts do you use (PICK 2) and what mass of each salt will you add to the mixture? H3PO4 (M.W.= 97.995) KH2PO4 (M.W.=136.086) Na2HPO4 (M.W.=141.959) AlPO4 (M.W.=121.953) 2
b). A concentrated phosphate buffer known as âphosphate buffered salineâ (or PBS) is made with the salts you choose from above in addition to NaCl and KCl. The 10x concentrated solution has a pH ~6.8 and the 1x concentrated (i.e., diluted with water) solution is ~7.1. Why?
c). You accidently grabbed the 10x concentrated phosphate buffered saline (or 10xPBS) instead of the 1xPBS solution and start to adjust the pH of your buffer with NaOH to reach your desired buffer pH. You notice it is taking much more base than with your usual 1xPBS buffer. Why?
Related textbook solutions
Basic Chemistry
Principles of Chemistry Molecular Approach
Chemistry: Structure and Properties
Principles of Chemistry Molecular Approach
Chemistry: A Molecular Approach
Chemistry: A Molecular Approach
Principles of Chemistry: A Molecular Approach
