A solution is made by dissolving 18.9 g of HCl in enough water to make 716 mL of solution. Calculate the pH of the solution at 25 degrees C
To calculate the pH of a solution, we need to determine the concentration of hydronium ions (H3O+). The concentration of H3O+ can be found using the concept of molarity (M), which is defined as the number of moles of solute per liter of solution.
First, we need to calculate the number of moles of HCl in the solution. We can use the formula:
moles = mass / molar mass
The molar mass of HCl is approximately 36.46 g/mol.
moles of HCl = 18.9 g / 36.46 g/mol
moles of HCl ≈ 0.518 mol
Next, we need to calculate the concentration of HCl in the solution. We divide the number of moles of HCl by the volume of the solution in liters:
concentration (M) = moles / volume (L)
The volume of the solution is given as 716 mL, so we convert it to liters:
volume (L) = 716 mL / 1000 mL/L
volume (L) = 0.716 L
concentration (M) = 0.518 mol / 0.716 L
concentration (M) ≈ 0.723 M
Since HCl dissociates completely in water, the concentration of hydronium ions (H3O+) is equal to the concentration of HCl.
Thus, the concentration of H3O+ in the solution is approximately 0.723 M.
To calculate the pH, we use the equation:
pH = -log10(H3O+ concentration)
pH = -log10(0.723)
pH ≈ 0.14
Therefore, the pH of the solution at 25°C is approximately 0.14.