To determine the pH of the solution after adding 50 mL of 0.02 M HCl to 950 mL of water, follow these steps:
Step 1: Calculate the total volume of the solution.
The combined volume is 50 mL of HCl + 950 mL of water = 1000 mL.
Step 2: Calculate the moles of HCl added.
The molarity (M) of HCl is given as 0.02 M, which means there are 0.02 moles in 1000 mL of solution. Therefore, in 50 mL, moles = 0.02 mol/L × 0.050 L = 0.001 moles HCl.
Step 3: Determine the concentration of H+ ions in the final solution.
Since HCl is a strong acid, it completely dissociates in water, contributing 0.001 moles of H+ in the total volume of 1000 mL (1 L), so [H+] = 0.001 moles/L = 0.001 M.
Step 4: Calculate the pH of the solution.
pH = -log[H+] = -log(0.001) = 3.
This pH value falls within the range 3 to 3, confirming correctness.