A buffer at pH 7.45 is prepared by mixing solutions of KH2PO4 and K2HPO4. Which of the following ratios of [base]/[acid] is required? For phosphoric acid, Ka1 = 7.5 × 10-3 Ka2 = 6.2 × 10-8 Ka3 = 4.2 × 10-13

The pH of the mixed buffer will be

= 1.737

Explanation:

Buffer is prepared by mixing solutions of KH₂PO₄ and K₂HPO₄

H₂PO₄⁻ ⇄  HPO₄²⁻ + H⁺

Using Henderson equation

⇒         pH = pKa₂ + log

⇒      7.45  = -log(6.2 x 10⁻⁸) + log

⇒     log = 7.45 - 7.2

⇒           =

⇒          = 1.737

So, pH of Buffer solution is equal to 1.737

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

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~ trueboss72

the answer is true. hope it .