Question

Calculate the pH of a solution prepared by mixing: (Show your work for these calculations) pk of acetic acid is 4.75 a. two moles of sodium acetate with two moles of acetic acid. b. two moles of sodium acetate with one mole of acetic acid.

Answer 1

Step-by-step explanation:

To calculate pH you need to use Henderson-Hasselbalch formula:

pH = pka + log₁₀
`([A^-])/([HA])`

Where HA is the acid concentration and A⁻ is the conjugate base concentration.

The equilibrium of acetic acid is:

CH₃COOH ⇄ CH₃COO⁻ + H⁺ pka: 4,75

Where CH₃COOH is the acid and CH₃COO⁻ is the conjugate base.

Thus, Henderson-Hasselbalch formula for acetic acid equilibrium is:

pH = 4,75 + log₁₀
`([CH_(3)COO^-])/([CH_(3)COOH])`

a) The pH is:

pH = 4,75 + log₁₀
`([2 mol])/([2 mol])`

pH = 4,75

b) The pH is:

pH = 4,75 + log₁₀
`([2 mol])/([1mol])`

pH = 5,05

I hope it helps!