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?
379
views
17. Acid and Base Equilibrium
pH of Weak Acids
Multiple 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.
Related Videos
Related Practice
