pH of buffer is calculated by the equation: pH=pK, +log (base/acid). Where pK= -log Kg. For...

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pH of buffer is calculated by the equation: pH=pK, +log (base/acid). Where pK= -log Kg. For nitrous acid HONO2 Kg = 4.0.10-4;

Answer 1

Answer #1

moles of HNO2 added : 0.2 L * 0.6 mol/L = 0.12 moles

moles of NH3 added : 0.4 L * 0.1 mol/L = 0.04 moles

total volume = 0.6 L

Reaction : HNO₂ (aq) + NH₃ (aq) ===> NO₂- (aq) + NH₄+ (aq)

Excess reagent : HNO₂ (aq)

Thus Buffer : HNO₂ / NO₂-

pH = pKa + log [NO₂-] / [ HNO₂ ]

[NO₂-] = 0.04 moles/ 0.6 L = 0.067 M

[ HNO₂ ] = 0.08 moles/ 0.6 L = 0.133 M

pKa = 3.40

pH = 3.40 + log [0.0667 M / 0.133 M]

pH = 3.10

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Answer 2

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