# Problem: A buffer, consisting of H2PO4- and HPO42-, helps control the pH of physiological fluids. Many carbonated soft drinks also use this buffer system.What is the pH of a soft drink in which the major buffer ingredients are 6.6 g of NaH2PO4 and 8.3 g of Na2HPO4 per 355 mL of solution?

###### FREE Expert Solution

Given solution:

The solution is composed of 6.6 g of NaH2PO4 and 8.3 g of Na2HPO4 per 355 mL of solution.

•  the anion in NaH2PO4 is the weak acid
• sodium  group 1A  (+1) charge Na+  cation

Main group metals should have a +3 charge or higher to be considered acidic

Na+ +1 charge  neutral and will not contribute to pH

• H2PO4 → anion  weak acid

- concentration of H2PO4 = concentration of NaH2PO4

6.6 g NaH2PO4 in 355 mL solution

molar mass of NaH2PO119.98 g/mol

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###### Problem Details

A buffer, consisting of H2PO4- and HPO42-, helps control the pH of physiological fluids. Many carbonated soft drinks also use this buffer system.

What is the pH of a soft drink in which the major buffer ingredients are 6.6 g of NaH2PO4 and 8.3 g of Na2HPO4 per 355 mL of solution?