Calculate the pH of a solution formed by mixing 200.0 mL of 0.30 mol L^-1 HClO with 300.0 mL of 0.20 mol L^-1 KClO. The K_a for HClO is 2.9 × 10^-8. A) 5.99 B) 8.01 C) 7.54 D) 7.06 E) 6.46

Question

Quizplus · Accepted Answer

Step 1: Calculate the moles of HClO and KClO separately.
moles of HClO = (0.30 mol/L) × (0.200 L) = 0.06 mol
moles of KClO = (0.20 mol/L) × (0.300 L) = 0.06 mol
Step 2: Calculate the total moles of acid and conjugate base.
moles of acid = moles of HClO = 0.06 mol
moles of conjugate base = moles of KClO = 0.06 mol
Step 3: Calculate the concentration of the acid and conjugate base.
acid concentration = (0.06 mol) / (0.500 L) = 0.12 mol/L
conjugate base concentration = (0.06 mol) / (0.500 L) = 0.12 mol/L
Step 4: Use the Henderson-Hasselbalch equation to solve for pH.
pH = pKa + log([A-]/[HA])
pKa = -log(Ka) = -log(2.9 × 10-8) = 7.54
[A-]/[HA] = 1 (because the concentrations are equal)
pH = 7.54 + log(1) = 7.54
Therefore, the pH of the solution is 7.54, which is closest to choice C.

Calculate the PH of a Solution Formed by Mixing 200