5 marksBuffers and pH
CAPE Chemistry Unit 1 · 2015 · Paper 2 · Question 5(b)
Kₐ (H₂PO₄⁻) = 6.4 × 10⁻⁸ mol dm⁻³. Relative atomic mass: H = 1, Na = 23, O = 16, P = 31.
Calculate the pH of a soft drink in which the major buffer ingredients are 6.5 g of NaH₂PO₄ and 8.0 g of Na₂HPO₄ per 355 cm³ of solution.
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