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100 ml of a 0.1 mm buffer solution made from acetic acid and sodium acetate with ph 5.0 is diluted to 1 l. what is the ph of the diluted solution?

Sagot :

The pH of the diluted solution is 5.53.

Henderson–Hasselbalch equation for buffer solution:

pH = pKa + log(c(CH₃COO⁻)/c(CH₃COOH))

pH = 5.0 ⇒ c(H⁺) = 10⁻⁵ M

pKa = 4.75 ⇒ Ka = 1.78×10⁻⁵

log(cs/ck) =  5.0 - 4.75 = 0.25

c(CH₃COO⁻)/c(CH₃COO⁻) = 10∧(0.25) = 1.778

c(CH₃COO⁻) + c(CH₃COOH) = 0.1 mM

c(CH₃COO⁻) + c(CH₃COOH) = 1 × 10⁻⁴M

c(CH₃COOH) = 3.6x10⁻⁵ M; concentration of acetic acid before dilution

c(CH₃COOH) = 3.6x10⁻⁶ M; concentration of acetic acid after 10 times dilution

c(CH₃COO⁻) = 6.4x10⁻⁵ M; concentration of sodium acetate before dilution

c(CH₃COO⁻) = 6.4x10⁻⁶ M; concentration of sodium acetate after dilution

c(H⁺) = 10⁻⁶ M; concentration of hydrogen ions

After buffer solution is diluted to 1 l:

Ka = (c(CH₃COO⁻) + x) × (c(H⁺) + x) / (c(CH₃COOH) - x)

1.78×10⁻⁵ = (6.4x10⁻⁶ M + x) × (10⁻⁶ M + x) / (3.6x10⁻⁶ M - x)

x = 2.12×10⁻⁶ M

c(H⁺) = 10⁻⁶ M + 2.12×10⁻⁶ M

c(H⁺) = 3.12×10⁻⁶ M

pH = -logc(H⁺)

pH = -log3.12×10⁻⁶ M

pH = 5.53

More about diluted solution: brainly.com/question/24881505

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