Chemistry: The Molecular Science (5th Edition)

Published by Cengage Learning
ISBN 10: 1285199049
ISBN 13: 978-1-28519-904-7

Chapter 15 - Additional Aqueous Equilibria - Questions for Review and Thought - Topical Questions - Page 693: 14c


$Na_2HPO_4$ and $Na_3P{O_4}$ are not the best combination for a buffer solution with pH $\approx$ 7.

Work Step by Step

1. Identify the acid: $HP{O_4}^{2-}$. 2. Calculate its pKa: $pKa = -log(Ka)$ $pKa = -log( 4.6 \times 10^{- 13})$ $pKa = 12.34$ 3. Compare this number to 7. - It is not approximately 7, therefore, these compounds are not the best combination for a buffer with neutral pH.
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