Chemistry

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How do I calculate the amount of grams of Na2HPO4 and NaH2PO4 to prepare 200 mL of a buffer with an 8.25 pH so the sum of the concentrations of HPO4 and H2PO4 ions is 0.5 M? Does this involve writing a Ka expression and equilibrium? I am confused and Thanks for your help!

  • Chemistry -

    Sorry I don't know how it posted twice! Oops! :-)

  • Chemistry -

    See your other post. The HH equation is the secret weapon.

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