Multiple Choice
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?
17. Acid and Base Equilibrium
pH of Weak Acids
Struggling with General Chemistry?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Calculate the pH of the solution made by adding 0.50 mol of HOBr and 0.30 mol of KOBr to 1.00 L of water. The value of Ka for HOBr is 2.0 × 10⁻⁹. What is the pH of the solution?
A
9.26
B
4.74
C
3.00
D
7.00
Verified step by step guidance1
Identify the components of the solution: HOBr is a weak acid and KOBr is its conjugate base. This is a buffer solution.
Use the Henderson-Hasselbalch equation to find the pH of the buffer solution: \( \text{pH} = \text{pKa} + \log \left( \frac{[A^-]}{[HA]} \right) \).
Calculate \( \text{pKa} \) using the given \( \text{Ka} \) value: \( \text{pKa} = -\log(\text{Ka}) \). Substitute \( \text{Ka} = 2.0 \times 10^{-9} \) into the equation.
Determine the concentrations of the acid \([HA]\) and the conjugate base \([A^-]\): Since the solution is 1.00 L, \([HA] = 0.50 \text{ M}\) and \([A^-] = 0.30 \text{ M}\).
Substitute the values of \( \text{pKa} \), \([A^-]\), and \([HA]\) into the Henderson-Hasselbalch equation to calculate the pH.
0:44mWatch next
Master ICE Charts of Weak Acids with a bite sized video explanation from Jules
Start learningRelated Videos
Related Practice
pH of Weak Acids practice set
Problem sets built by lead tutorsExpert video explanations