Question
What is pH of an aqueous solution that is 0.0030M pyruvic acid
Answers
Answered by
GPT 3.5
The pH of an aqueous solution depends on the dissociation of the acid. Pyruvic acid (CH3COCOOH) is a weak acid that partially dissociates in water. To calculate the pH, we need to know the dissociation constant (Ka) of pyruvic acid.
The Ka for pyruvic acid is approximately 0.00018. Since the concentration of pyruvic acid is 0.0030 M, we can assume that the concentration of the dissociated form (CH3COCOO-) is very small compared to the concentration of the undissociated form (CH3COCOOH) due to its weak acidity.
Therefore, we can assume that the concentration of CH3COCOO- is negligible and the concentration of CH3COCOOH is approximately equal to 0.0030 M.
Since the concentration of the dissociated form is negligible compared to the concentration of the undissociated form, we can consider the concentration of the undissociated form as the initial concentration of the acid.
Using the equation for the dissociation of pyruvic acid: CH3COCOOH <-> CH3COCOO- + H+, we can write the equation for the dissociation constant:
Ka = [CH3COCOO-][H+]/[CH3COCOOH]
Since the concentration of CH3COCOO- is negligible, we can ignore it in the equation, which simplifies to:
Ka = [H+]/[CH3COCOOH]
Let x be the concentration of H+ ions in the solution (which is also the concentration of H+ ions from the dissociation of pyruvic acid).
Ka = x/0.0030
Rearranging the equation to solve for x:
x = Ka * [CH3COCOOH] = 0.00018 * 0.0030 = 0.00000054
Now, we can calculate the pH using the equation: pH = -log[H+]
pH = -log(0.00000054) ≈ 5.27
So, the pH of a 0.0030 M pyruvic acid solution is approximately 5.27.
The Ka for pyruvic acid is approximately 0.00018. Since the concentration of pyruvic acid is 0.0030 M, we can assume that the concentration of the dissociated form (CH3COCOO-) is very small compared to the concentration of the undissociated form (CH3COCOOH) due to its weak acidity.
Therefore, we can assume that the concentration of CH3COCOO- is negligible and the concentration of CH3COCOOH is approximately equal to 0.0030 M.
Since the concentration of the dissociated form is negligible compared to the concentration of the undissociated form, we can consider the concentration of the undissociated form as the initial concentration of the acid.
Using the equation for the dissociation of pyruvic acid: CH3COCOOH <-> CH3COCOO- + H+, we can write the equation for the dissociation constant:
Ka = [CH3COCOO-][H+]/[CH3COCOOH]
Since the concentration of CH3COCOO- is negligible, we can ignore it in the equation, which simplifies to:
Ka = [H+]/[CH3COCOOH]
Let x be the concentration of H+ ions in the solution (which is also the concentration of H+ ions from the dissociation of pyruvic acid).
Ka = x/0.0030
Rearranging the equation to solve for x:
x = Ka * [CH3COCOOH] = 0.00018 * 0.0030 = 0.00000054
Now, we can calculate the pH using the equation: pH = -log[H+]
pH = -log(0.00000054) ≈ 5.27
So, the pH of a 0.0030 M pyruvic acid solution is approximately 5.27.