Chapter 17, Problem 70IAE

You are asked to prepare a ${\text{KH}}_{\text{2}}{\text{PO}}_{\text{4}}{\text{-Na}}_{\text{2}}{\text{HPO}}_{\text{2}}$ solution that has the same pH as human blood, 7.40.

1. What should be the ratio of concentrations $\left[{\text{HPO}}_{\text{4}}^{\text{2-}}\right]/\left[{\text{H}}_{\text{2}}{\text{PO}}_{\text{4}}^{\text{-}}\right]$ in this solution?

Suppose you have to prepare 1.00 L of the solution described part (a) and that this solution must be isotonic with blood (have the same osmotic pressure as blood). What masses of ${\text{KH}}_{\text{2}}{\text{PO}}_{\text{4}}$ and of ${\text{KH}}_{\text{2}}{\text{HPO}}_{\text{4}}\cdot 12{\text{H}}_{\text{2}}\text{O}$ would you use [Hint: Refer to the definition of isotonic on page 68. Recall that a solution of NaCI 9.2g NaCl/L solution is isotonic blood, and assume that NaCI is completely ionized m aqueous solution.]