Question

A 2.17 g sample of acetylsalicylic acid required 23.88 mL of 0.5043 M NaOH for complete reaction. Addition of 13.46 mL of 0.4472 M HCl to the flask containing the aspirin and the sodium hydroxide produced a mixture with pH

Answer 1

The pH of the mixture is 0.7926

Step-by-step explanation:

Hi there!

The acetylsalicylic acid was completely neutralized by the sodium hydroxide so that the only protons present in the solution come from the HCl. The volume of the solution can be calculated as the addition of the volume of sodium hydroxide and the volume of HCl (assuming that the mixture is an ideal solution).

The number of moles of HCl added can be calculated as follows:

13.46 ml (0.4472 mol/1000 ml) = 6.019 × 10⁻³ mol

The volume of the solution is 13.46 ml + 23.88 ml = 37.34 ml

Then, we can calculate the concetration of protons in the solution:

[H] = 6.019 × 10⁻³ mol /0.03734 l = 0.1612 M

The pH of the mixture:

pH = -log[H]

pH = -log[0.1612] = 0.7926