We have to determine the volume of 36.0 % by mass HCl solution required to prepare 4.95 L of a solution with a pH of 1.8.

**Recall:** halogen binary acids are strong acids, except HF.

HCl is a strong acid and dissociates completely in solution.

HCl → H^{+} + Cl^{-}

**We will solve this problem through these steps:**

**Step 1:** Calculate the concentration of final solution using the given pH.

**Step 2:** Calculate the molarity of 36.0 % by mass HCl solution (stock solution).

**Step 3:** Use the dilution formula and calculate the required volume.

What volume of a concentrated HCl solution, which is 36.0% HCl by mass and has a density of 1.179 g/mL, should be used to make 4.95 L of an HCl solution with a pH of 1.8?