Hydrochloric acid (HCl) is commonly sold as a pool additive, where it is used to lower the pH of the pool water if it is too high. Swimming pools are commonly kept between a pH of 7.0 - 7.6 to ensure the comfort of the swimmers. You find a bottle of HCl in the pool aisle at the hardware store which is labelled as having a concentration of 147 g/L. What is the pH of this solution, to 2 decimal places? The molar mass of HCl is 36.46 g/mol.Remember: pH = -log10[H3O+(aq)], pOH = -log10[OH-(aq)] and pH + pOH = 14.00

To find the pH of the solution, we first need to find the molarity of the HCl solution.

1. Calculate the molarity (M) of the HCl solution. Molarity is defined as the number of moles of solute per liter of solution.

   Given that the concentration of HCl is 147 g/L and the molar mass of HCl is 36.46 g/mol, we can calculate the molarity as follows:

   Molarity = (147 g/L) / (36.46 g/mol) = 4.03 mol/L

2. The concentration of H3O+ ions in a solution of a strong acid like HCl is equal to the molarity of the acid. This is because HCl completely ionizes in water to form H3O+ and Cl- ions. Therefore, [H3O+] = 4.03 mol/L.

3. Now we can calculate the pH of the solution using the formula pH = -log10[H3O+].

   pH = -log10(4.03) = -0.605

4. However, pH values are always reported as positive numbers, so we take the absolute value of -0.605 to get the pH of the solution.

   pH = 0.605

5. The pH value is usually rounded to two decimal places, so the pH of the HCl solution is approximately 0.61.

Please note that this is a very low pH, indicating a highly acidic solution, as expected for a strong acid like HCl.