Acetic Acid Acid Dissociation Constant

Calculate pH of Acetic Acid (CH3COOH) | Examples | Online Calculator

Acetic acid (CH₃COOH) is a weak carboxylic acid. That means, acetic acid solution contains very low H⁺ ion concentration compared to equilibrium acerb acid concentration. Therefore, pH value of acetic acid solution is greater than HCl acrid at aforementioned concentration solutions.

CH₃COOH_(aq) + H₂O_(l) ⇌ CH₃COO^- _(aq) + H₃O⁺ _(aq)

In this tutorial, nosotros will discuss following sections.

Dissociation of acetic acrid
Summate pH of acerb acrid past using Yard_a value
pH values of common acetic acid solution
Online reckoner
pH values of acerb acid at different concentrations

Dissociation of acetic acid

Acerb acid dissociates poorly in water to acetate ion and hydronium ion. This reaction is reversible and equilibrium point is shifted to left side (In strong acids such every bit HCl, equilibrium point is shifted to right side). That means, concentration of acetic acid is very much higher than concentrations of acetate ion and H⁺ ions.

Summate pH of acetic acrid past using K_a value

Subsequently writing down the equation of dissociation reaction, expression of dissociation abiding is written. Equilibrium concentrations of compounds and ions should be substituted to the terms in the equation. Equilibrium concentrations are determined as following past creating a table.

acetic acid pH calculation

Acetic acrid is a weak acrid. Therefore, dissociated concentration is very small-scale compared to the initial concentration of acetic acid. Therefore, we make an supposition of equilibrium concentration of acetic acrid is same every bit the initial concentration of acerb acid. And so, nosotros can substitute the equilibrium concentration of acetic acid (CH₃COOH), acetate ion (CH₃COO^-)and hydronium ion (H₃O⁺) to the equation.

Calculate pH of acetic acid by using Ka value

Now, nosotros know the concentration of H⁺ (H_threeO⁺) ions.

x = [H₃O⁺ _(aq)] = [CH_threeCOO^- _(aq)] = 1.34 * 10^-iii mol dm^-3

Assumptions made in calculations

H₃O⁺ is given by water is neglected because dissociation of water is very depression compared to the acerb acid dissociation.

Because H₃O⁺ concentration is known now, pH value of acetic acid solution can be calculated.

pH = -log[H₃O⁺ _(aq)]
pH = -log[i.34 * 10^-3]
pH = two.88

pH Calculator of aqueous acetic acrid solution

K_a value of acerb acrid at 25⁰C is taken as i.8 * 10^-5 mol dm^-3.

Concentration of acetic acrid (mol dm^-three)

Try: weak acid pH online computer

pH values of acerb acid at unlike concentrations

Concentration of acetic acid (mol dm^-3)	pH
0.1	ii.87
0.05	iii.02
0.01	3.37
0.005	iii.52
0.001	3.87
1	2.37

When acerb acrid solution is diluted by 10 times, it's pH value is increased by 0.5. As an case, 0.1 mol dm^-3 acetic acrid is diluted upto 0.01 mol dm^-3, pH value is increased from 2.87 to 3.37.

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