Calculate the [CH3CO2H] in a solution if it has a pH 3.21.
CH3CO2H = CH3CO2- + H+
pH = 3.21
3.21 = -log(H^+). Solve for (H^+) equal ESTIMATED 6.2E-4 but you should do it more accurately.
Call CH3COOH =-HAc
........HAc ==> H^+ + Ac^-
I.......x.......0......0
C.....6.2E-4..6.2E-4..6.2E-4
E....x-6.2E-4..6.2E-4.6.2E-
K = (H^+)(Ac^-)/(HAc)
Substitute and solve for x.
To calculate the concentration of CH3CO2H (acetic acid) in a solution with a given pH, we need to use the relationship between pH and the concentration of H+ ions.
1. Start by converting the pH value to the concentration of H+ ions using the equation: pH = -log[H+]. Rearrange the equation to solve for [H+]: [H+] = 10^(-pH).
In this case, the pH is given as 3.21. Let's calculate the concentration of H+ ions:
[H+] = 10^(-3.21)
[H+] = 5.01 x 10^(-4) M (Molar)
2. Acetic acid (CH3CO2H) is a weak acid, which means it partially dissociates in water. The dissociation equation is CH3CO2H ⇌ CH3CO2- + H+.
The equilibrium constant expression for this dissociation is given by the acid dissociation constant (Ka): Ka = [CH3CO2-][H+] / [CH3CO2H].
3. We can assume that the concentration of CH3CO2- at equilibrium is equal to the concentration of H+ ions ([CH3CO2-] ≈ [H+]) because acetic acid is a weak acid.
4. Therefore, we can rewrite the Ka expression as: Ka = [H+]^2 / [CH3CO2H].
5. Rearranging the equation, we can solve for [CH3CO2H]: [CH3CO2H] = [H+]^2 / Ka.
The Ka value for acetic acid is 1.8 x 10^(-5) M. Let's calculate the concentration of CH3CO2H:
[CH3CO2H] = (5.01 x 10^(-4))^2 / (1.8 x 10^(-5))
[CH3CO2H] ≈ 13.9 M (approximately)
Therefore, the concentration of CH3CO2H in the solution is approximately 13.9 M.