Calculate the pH of a 0.1 M acetic acid solution (Ka = 1.8 x 10^-5).

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Question: Calculate the pH of a 0.1 M acetic acid solution (Ka = 1.8 x 10^-5).

Options:

Correct Answer: 3.87

Solution:

Using the formula for weak acids, pH = 0.5(pKa - log[C]), where pKa = -log(1.8 x 10^-5) ≈ 4.74. Thus, pH = 0.5(4.74 - log(0.1)) = 3.87.

Calculate the pH of a 0.1 M acetic acid solution (Ka = 1.8 x 10^-5).

Calculate the pH of a 0.1 M acetic acid solution (Ka = 1.8 x 10^-5).

Step 1: Identify the concentration of acetic acid, which is 0.1 M.
Step 2: Find the acid dissociation constant (Ka) for acetic acid, which is 1.8 x 10^-5.
Step 3: Calculate the pKa using the formula pKa = -log(Ka). So, pKa = -log(1.8 x 10^-5).
Step 4: Use a calculator to find pKa. This gives approximately 4.74.
Step 5: Use the formula for weak acids to find pH: pH = 0.5(pKa - log[C]). Here, [C] is the concentration of the acid, which is 0.1.
Step 6: Calculate log(0.1). This is equal to -1.
Step 7: Substitute the values into the pH formula: pH = 0.5(4.74 - (-1)).
Step 8: Simplify the equation: pH = 0.5(4.74 + 1) = 0.5(5.74).
Step 9: Calculate the final pH: pH = 2.87.

Weak Acid Equilibrium – Understanding the dissociation of weak acids and the use of the acid dissociation constant (Ka) to calculate pH.
pKa Calculation – Calculating pKa from Ka using the formula pKa = -log(Ka).
Logarithmic Functions – Applying logarithmic functions in the context of pH calculations.