One Drop, 0

question 2

Multiple Choice

One drop, 0.200 cm³, of 1.00 mol dm^-3 of aqueous sodium hydroxide, NaOH, solution, is added to 25.0 cm³ of a phosphate buffer that is 0.040 mol dm^-3 in KH₂PO₄(aq) and 0.020 mol dm⁻³ in K₂HPO₄(aq) . Calculate the resulting pH of the solution given that the second acid dissociation constant, pK_a2, for phosphoric acid is 7.21.

• A) 7.21
• B) 6.91
• C) 7.16
• D) 7.27

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