Answer the following two questions about the equivalence point for the titration of 27.8 mL of 0.235 M hypobromous acid (pKa = 8.64) with 0.214 M KOH.
1)Predict if the solution will be acidic, basic or neutral at the equivalence point.
2)Calculate the pH of the solution at the equivalence point.
Answered at your other post.
To answer these questions, we need to understand the concept of the equivalence point in a titration. The equivalence point is the point in a titration where the stoichiometrically equivalent amounts of the acid and base have reacted, resulting in neutralization. At this point, the moles of acid are equal to the moles of base, and the solution is neutral.
1) To predict if the solution will be acidic, basic, or neutral at the equivalence point, we need to compare the strength of the acid and base involved in the titration. In this case, we have hypobromous acid (HBrO) and potassium hydroxide (KOH).
Hypobromous acid is a weak acid with a pKa of 8.64. A pKa value indicates the acidity of an acid. The lower the pKa value, the stronger the acid. Since the pKa of HBrO is greater than 7, it means HBrO is a weak acid.
On the other hand, potassium hydroxide (KOH) is a strong base. Strong bases completely dissociate in water, resulting in the formation of hydroxide ions (OH-).
When a weak acid reacts with a strong base, the resulting solution will be basic at the equivalence point. Therefore, the solution will be basic at the equivalence point.
2) To calculate the pH of the solution at the equivalence point, we need to determine the concentration of the resulting solution. The moles of hypobromous acid (HBrO) can be calculated using the equation:
moles HBrO = volume (in liters) × molarity
Given: volume of HBrO = 27.8 mL = 0.0278 L
molarity of HBrO = 0.235 M
moles HBrO = 0.0278 L × 0.235 M = 0.006523 mol
Since HBrO reacts stoichiometrically with KOH, the moles of KOH will be equal to the moles of HBrO. In this case, the number of moles of KOH is also 0.006523 mol.
At the equivalence point, the moles of the acid and base have neutralized each other. Therefore, the concentration of OH- ions will be equal to the concentration of the remaining KOH. This can be found by dividing the number of moles of KOH by the total volume of the solution.
Total volume of the solution = volume of HBrO + volume of KOH
Given: volume of HBrO = 27.8 mL = 0.0278 L
volume of KOH = unknown, let's call it "V"
Total volume = 0.0278 L + V
Since the concentration of KOH is 0.214 M, we can set up an equation to relate the concentration, volume, and moles:
0.214 M × (0.0278 L + V) = 0.006523 mol
Solving this equation will give us the value of V, which represents the volume of KOH used in the titration. Once we know the volume of KOH, we can determine the concentration of OH- ions.
Finally, we can calculate the pOH of the solution using the concentration of OH-. The pH can be found using the equation: pH = 14 - pOH.
By following these steps, you can calculate the pH of the solution at the equivalence point.