What is the pH of a solution prepared by dissolving 7.5 g HCl in water to make 415 mL of solution?
moles HCl = grams/molar mass.
M = moles/L soln.
To find the pH of a solution prepared by dissolving 7.5 g of HCl in water to make 415 mL of solution, we need to use the concept of molarity.
First, we need to calculate the number of moles of HCl using its molecular weight. The molecular weight of HCl is the sum of the atomic weights of hydrogen (H) and chlorine (Cl), which is approximately 1 + 35.5 = 36.5 g/mol.
The number of moles of HCl can be calculated using the formula: Moles = Mass / Molecular Weight. Therefore, Moles = 7.5 g / 36.5 g/mol.
Once we have the number of moles, we can then calculate the molarity (M) of the solution, which is defined as Moles of solute / Liters of solution. In this case, we divide the moles by the volume of the solution, converted from mL to L: 415 mL = 415/1000 = 0.415 L.
Molarity (M) = Moles / Volume (L). Therefore, M = (7.5 g / 36.5 g/mol) / 0.415 L.
Now that we have the molarity of the solution, we can determine the pH. The pH of a solution can be calculated using the equation: pH = -log[H+], where [H+] represents the hydrogen ion concentration.
In the case of HCl, it is a strong acid and completely dissociates in water, producing an equal concentration of hydrogen ions (H+) and chloride ions (Cl-). Therefore, the concentration of H+ is equal to the molarity of the HCl solution.
Finally, we can find the pH by taking the negative logarithm of the hydrogen ion concentration. pH = -log[H+].
By plugging in the calculated molarity (M), we can find the pH of the solution prepared by dissolving 7.5 g of HCl in water to make 415 mL of solution.