a buffer solution is 0.2M in acetic acid and in sodium acetate. Calculate the change in pH upon adding 1.0ml of 0.1M hydrochloric acid to 10ml of this solution.(Given pKA of acetic acid is 4.76)
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Calculate millimols HAc and mmols NaAc and plug into the HH equation and solve for pH.
Then use an ICE chart, add the mmoles HCl and complete the E line of the ICE table. Then plug into the HH equation again and solve for pH.
To calculate the change in pH upon adding hydrochloric acid to the buffer solution, we first need to determine the initial pH of the buffer.
A buffer solution is composed of a weak acid and its conjugate base, which in this case is acetic acid (CH3COOH) and sodium acetate (CH3COONa), respectively. The pKa value of acetic acid is given as 4.76.
To find the initial pH of the buffer, we can use the Henderson-Hasselbalch equation:
pH = pKa + log([A-]/[HA])
Where [A-] represents the concentration of the conjugate base (sodium acetate) and [HA] represents the concentration of the weak acid (acetic acid).
Given that the buffer is 0.2M in both acetic acid and sodium acetate, the concentration of both [A-] and [HA] will be 0.2M.
Substituting these values into the Henderson-Hasselbalch equation:
pH = 4.76 + log(0.2/0.2)
pH = 4.76 + log(1)
pH = 4.76 + 0
pH = 4.76
Therefore, the initial pH of the buffer solution is 4.76.
Now, let's calculate the change in pH upon adding 1.0ml of 0.1M hydrochloric acid to 10ml of this buffer solution.
Since the volumes of the buffer and the added acid are given in different units (ml and M), we need to convert them to a common unit. Let's convert the volume of the hydrochloric acid to liters:
1.0ml = 1.0 x 10^-3 L
Now we can calculate the moles of hydrochloric acid added:
moles of HCl = concentration x volume
= 0.1M x 1.0 x 10^-3 L
= 1.0 x 10^-4 moles
Since hydrochloric acid is a strong acid, it will completely dissociate in water, resulting in the formation of hydronium ions (H3O+). So, the concentration of hydronium ions will be equal to the concentration of HCl added:
[H3O+]added = 0.1M
To calculate the change in pH, we can use the equation:
ΔpH = -log([H3O+]added)
Substituting the value:
ΔpH = -log(0.1)
Δ𝑝𝐻 = -(-1)
Δ𝑝𝐻 = 1
Therefore, the change in pH upon adding 1.0ml of 0.1M hydrochloric acid to 10ml of the given buffer solution is 1.