Open Question
Find the pH of each mixture of acids. b. 0.150 M in HNO2 and 0.085 M in HNO3 c. 0.185 M in HCHO2 and 0.225 M in HC2H3O2 d. 0.050 M in acetic acid and 0.050 M in hydrocyanic acid
17. Acid and Base Equilibrium
pH of Weak Acids
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A particular sample of vinegar has a pH of 2.90. If acetic acid is the only acid that vinegar contains, what is the concentration of acetic acid in the vinegar?
A
0.001 M
B
0.01 M
C
0.005 M
D
0.02 M
Verified step by step guidance1
Understand that pH is a measure of the hydrogen ion concentration in a solution. The pH is given by the formula: \( \text{pH} = -\log[H^+] \).
Given the pH of the vinegar is 2.90, use the formula to find the concentration of hydrogen ions \([H^+]\). Rearrange the formula to solve for \([H^+]\): \([H^+] = 10^{-\text{pH}}\).
Substitute the given pH value into the equation: \([H^+] = 10^{-2.90}\). This will give you the concentration of hydrogen ions in the solution.
Recognize that acetic acid (CH₃COOH) is a weak acid and partially dissociates in water. The dissociation can be represented as: \( \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \).
Assume that the concentration of \([H^+]\) is approximately equal to the initial concentration of acetic acid due to its weak dissociation. Compare the calculated \([H^+]\) with the given options to determine the concentration of acetic acid.
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