What is the pH at the equivalence point for the titration between sodium hydroxide and acetic acid?
Question
What is the pH at the equivalence point for the titration between sodium hydroxide and acetic acid?
Solution
Sure, I can help with that. The pH at the equivalence point of a titration between a strong base (like sodium hydroxide) and a weak acid (like acetic acid) is determined by the hydrolysis of the anion produced from the weak acid (acetate ion in this case).
Here are the steps to calculate it:
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Write the hydrolysis reaction for the acetate ion: CH3COO- + H2O -> CH3COOH + OH-
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Write the expression for the equilibrium constant for this reaction (Kb for the acetate ion). This can be calculated from the Ka of the acetic acid and the Kw of water: Kb = Kw / Ka Where Kw is the ion product of water (1.0 x 10^-14 at 25°C) and Ka is the acid dissociation constant for acetic acid (1.8 x 10^-5).
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Write the expression for the concentration of OH- ions at equilibrium in terms of Kb and the initial concentration of the acetate ion ([CH3COO-]0): [OH-] = sqrt(Kb * [CH3COO-]0)
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Calculate the pOH of the solution at the equivalence point by taking the negative logarithm (base 10) of the OH- concentration: pOH = -log10([OH-])
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Finally, calculate the pH of the solution at the equivalence point by subtracting the pOH from 14: pH = 14 - pOH
This will give you the pH at the equivalence point for the titration between sodium hydroxide and acetic acid.
Similar Questions
Solid sodium hydroxide is slowly added to 1 L solution of 0.59 M acetic acid (CH3COOH). What is the pH of the equivalence point where just enough sodium hydroxide has been added to completely react with the acetic acid in solution?The pKa of acetic acid is 4.76Some useful formulas:pKa + pKb = 14𝑝𝐾𝑏=−log10𝐾𝑏[𝑂𝐻−]=𝐾𝑏×[𝐶𝐻3𝐶𝑂𝑂−]𝑝𝑂𝐻=−log10[𝑂𝐻−]pH + pOH = 14
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