Multiple Choice
Which of the following titration curves expresses the titration of a weak acid with a strong base?
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2. Water
Titration
Multiple Choice
Titration confirms an acetic acid solution to be 0.1 M. Calculate the pH. (acetic acid K a = 1.76 x 10-5 M).
A
2.1
B
3.6
C
2.9
D
8.3
Verified step by step guidance1
Identify the given values: the concentration of acetic acid (CH3COOH) is 0.1 M, and the acid dissociation constant (Ka) for acetic acid is 1.76 x 10^-5 M.
Write the equilibrium expression for the dissociation of acetic acid: CH3COOH ⇌ H+ + CH3COO-. The equilibrium constant expression is Ka = [H+][CH3COO-]/[CH3COOH].
Assume that the initial concentration of H+ and CH3COO- is 0, and let x be the concentration of H+ and CH3COO- at equilibrium. Therefore, [H+] = [CH3COO-] = x and [CH3COOH] = 0.1 - x.
Substitute these values into the equilibrium expression: 1.76 x 10^-5 = (x)(x)/(0.1 - x). Since Ka is small, assume x << 0.1, simplifying the expression to 1.76 x 10^-5 ≈ x^2/0.1.
Solve for x, which represents the concentration of H+ ions. Then, calculate the pH using the formula pH = -log[H+].
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