If 15.0 mL of glacial acetic acid (pure HC2H3O2) is diluted to 1.50 L with water, what is the pH of the resulting solution? THe density of glacial acetic acid is 1.05 g/mL
Disregard this question, I figured it out!
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I'd like to know the answer! haha
To find the pH of a solution, we need to determine the concentration of H⁺ ions in the solution. In this case, we are diluting glacial acetic acid with water.
First, we need to calculate the number of moles of glacial acetic acid (HC2H3O2) used. Given that the density of glacial acetic acid is 1.05 g/mL, we can find the mass of the glacial acetic acid used:
Mass of glacial acetic acid = volume of glacial acetic acid × density of glacial acetic acid
= 15.0 mL × 1.05 g/mL
= 15.75 g
Next, we need to convert the mass of glacial acetic acid to moles. To do this, we need to know the molar mass of glacial acetic acid, which is calculated by adding up the atomic masses of its elements:
Molar mass of HC2H3O2 = (1 × atomic mass of H) + (2 × atomic mass of C) + (3 × atomic mass of H) + (2 × atomic mass of O)
= (1 × 1.01 g/mol) + (2 × 12.01 g/mol) + (3 × 1.01 g/mol) + (2 × 16.00 g/mol)
= 60.05 g/mol
Number of moles of HC2H3O2 = Mass of glacial acetic acid / Molar mass of HC2H3O2
= 15.75 g / 60.05 g/mol
≈ 0.2627 mol
Now that we know the number of moles of HC2H3O2, we can calculate its concentration in the final solution.
Concentration of HC2H3O2 = Number of moles of HC2H3O2 / Volume of the final solution
= 0.2627 mol / 1.50 L
≈ 0.175 mol/L
Since acetic acid (HC2H3O2) is a weak acid, it does not completely dissociate into H⁺ ions. Instead, it partially dissociates according to the equation:
HC2H3O2 + H2O ⇌ H3O⁺ + C2H3O2⁻
To determine the pH of the resulting solution, we need to find the concentration of H⁺ ions. Since the acid is weak, we can assume that at equilibrium, the concentrations of H2O and C2H3O2⁻ are essentially constant, and their effects on the concentration of H⁺ can be neglected. Therefore, the concentration of H⁺ ions is equal to the concentration of HC2H3O2.
Concentration of H⁺ ions = Concentration of HC2H3O2
≈ 0.175 mol/L
Finally, we can calculate the pH of the solution using the formula:
pH = -log[H⁺]
pH = -log(0.175)
≈ 0.757
Therefore, the pH of the resulting solution is approximately 0.757.