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# 10.00 grams of KH2PO4 (FW = 136.086 g/mol) are dissolved in 500 mL of deionized H2O....

10.00 grams of KH2PO4 (FW = 136.086 g/mol) are dissolved in 500 mL of deionized H2O. How many grams Na2HPO4 (FW = 141.96 g/mol) need to be dissolved to create a solution with a pH of 6.90? For H3PO4, pKa1 = 2.15 , pKa2 = 7.20, and pKa3 = 12.37.

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