You need to make a buffer whose pH is 7.0, and you can choose from the weak acids shown in Table 2.6. Briefly explain your choice.

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TABLE 2.6 Some weak acids and their conjugate bases Acid (Proton Donor) HCOOH Formic acid CH3COOH Acetic acid OH CH₂CH-COOH Lactic acid H₂PO4 Phosphoric acid H₂PO4 Dihydrogen phosphate ion HPO ²- Monohydrogen phosphate ion H₂CO3 Carbonic acid HCO3 Bicarbonate ion C6H5OH Phenol NHA Ammonium ion 11 11 11 1 Conjugate Base (Proton Acceptor) HCOO Formate ion CH₂COO- Acetate ion OH T CH₂CH-COO Lactate ion H₂PO4 Dihydrogen phosphate ion HPO₂²- Monohydrogen phosphate ion PO ³- Phosphate ion HCO3 Bicarbonate ion CO3²- Carbonate ion C6H5O Phenolate ion NH3 Ammonia +H+ +H+ +H+ +H+ +H+ +H+ +H+ +H* +H+ +H+ pK₂ 3.75 4.76 3.86 2.14 6.86 12.4 6.3* 10.25 9.89 9.25 K₂ (M) 1.78 x 10-4 1.74 x 10-5 1.38 x 10-4 7.24 x 10-3 1.38 x 10-7 3.98 x 10-13 5.1 x 10-7* 5.62 X 10-11 1.29 X 10-10 5.62 x 10-10