What is the pH when 10 mL of 1 M acetic acid is added to pure water so that the final volume is 100 mL? The Ka for acetic acid is 1.74 x 10^(-5)
To determine the pH of the solution, we need to calculate the concentration of acetic acid in the final solution.
Step 1: Calculate the moles of acetic acid added:
Moles of acetic acid = volume (in liters) × concentration
= 0.01 L × 1 M
= 0.01 moles
Step 2: Calculate the total volume of the final solution:
Final volume = volume of acetic acid + volume of water
= 0.01 L + 0.1 L
= 0.11 L
Step 3: Calculate the concentration of acetic acid in the final solution:
Concentration = moles / volume
= 0.01 moles / 0.11 L
≈ 0.091 M
Step 4: Calculate the pKa from the Ka value:
pKa = -log(Ka)
= -log(1.74 × 10^(-5))
≈ 4.76
Step 5: Calculate the concentration of hydrogen ions (H+) in the solution:
[H+] = √(Ka × C)
= √(1.74 × 10^(-5) × 0.091)
≈ 2.449 × 10^(-3) M
Step 6: Calculate the pH of the solution:
pH = -log[H+]
= -log(2.449 × 10^(-3))
≈ 2.61
Therefore, when 10 mL of 1 M acetic acid is added to pure water to obtain a final volume of 100 mL, the pH of the solution is approximately 2.61.