Question

g If 50.0 mL of a 0.75 M acetic acid solution is titrated with 1.0 M sodium hydroxide, what is the pH after 10.0 mL of NaOH have been added

Answer 1

pH = 2.66

Step-by-step explanation:

• Acetic Acid + NaOH → Sodium Acetate + H₂O

First we calculate the number of moles of each reactant, using the given volumes and concentrations:

• 0.75 M Acetic acid * 50.0 mL = 37.5 mmol acetic acid

• 1.0 M NaOH * 10.0 mL = 10 mmol NaOH

We calculate how many acetic acid moles remain after the reaction:

• 37.5 mmol - 10 mmol = 27.5 mmol acetic acid

We now calculate the molar concentration of acetic acid after the reaction:

27.5 mmol / (50.0 mL + 10.0 mL) = 0.458 M

Then we calculate [H⁺], using the following formula for weak acid solutions:

• [H⁺] =
  `√(C*Ka)=\sqrt{0.458M*1.76x10^(-5)}`

• [H⁺] = 0.0028

Finally we calculate the pH:

• pH = -log[H⁺]

• pH = 2.66