Part I) 1) Calculate the pH of a buffer solution prepared by dissolving 0.2 mole

Question

Part I)

1) Calculate the pH of a buffer solution prepared by dissolving 0.2 mole of sodium cyanate (NaCNO) and 1.0 mole of cyanic acid (HCNO) in enough water to make 1.0 liter of solution. [Ka(HCNO) = 2.0 × 10–4]

2) Consider a buffer solution prepared from CH3COOH and NaCH3COOH . Which is the net ionic equation (no spectators) for the reaction that occurs when NaOH is added to this buffer?

a) OH– + CH3COOH   H2O + CH3COO –

   b) OH– + CH3COO – CH3COOH + O2–

   c) Na+ + CH3COOH   NaCH3COO + OH–

   d) H+ + CH3COOH   H2 + CH3COO–

e) NaOH + CH3COOH   H2O + NaCH3COO

Part II)

1) What is the net ionic equation for the reaction that occurs when small amounts of hydrochloric acid are added to a CH3COOH /NaCH3COO buffer solution?

a) H+ + H2O H3O+

b) H+ + CH3COO –   CH3COOH

c) CH3COOH H+ + CH3COO –

d) H+ + CH3COOH H2OCH3COO +

e) HCl + CH3COOH H2 + CH3COOCl-

Explanation / Answer

1) Calculate the pH of a buffer solution prepared by dissolving 0.2 mole of sodium cyanate (NaCNO) and 1.0 mole of cyanic acid (HCNO) in enough water to make 1.0 liter of solution. [Ka(HCNO) = 2.0 × 10–4]

this ia buffer so

pKa = -logKa) = -log(2*10^-4) =3.69897

pH = pKa + log(conjugate/acid)

pH = 3.69897+ log(0.2/0.1) = 3.99999

pH = 4

NOTE;consider posting multiple questions in differente set of Q&A. We ar enot allowed to answer to multiple questions in a single set of Q&A.

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