A 40.0 mL sample of a mixture of HCl and H3PO4 was titrated with 0.100 M NaOH. The first equivalence point was reached after 88.0 mL of base, and the second equiva-lence point was reached after 126.4 mL of base. (c) What percent of the HCl is neutralized at the first equivalence point?

Video transcript

Hey everyone, we're told that a 50 millimeter acquis solution contains hydrochloric acid and citric acid and was tight treated against a 0.15 molar solution of sodium hydroxide. The barrett readings volume of sodium hydroxide solution for the 1st and 2nd equivalence points were 74.8 millimeters and 87. mL, respectively, determine the percentage of hydrochloric acid that was neutralized at the first equivalence point. So first let's go ahead and write out our reaction. We know the hydrochloric acid is a strong acid that lionizes completely in the quickest solution. So we have hydro romick acid and this is going to react with our water. Now when these two react, we end up with our hydro ni um ions plus our browning ion. Now, as we know, citric acid is a weak acid. So the first ionization is going to be our citric acid and this is going to react with water as well. When these two react, we end up with our hydro ni um ions plus our citrate ion. So to answer this question, we know that the first equivalence point is reached when all of our hydroponic acid is consumed since it is mono product And when 3rd mole of citric acid is consumed since it is try protic. So in the presence of the strong acid hydrochloric acid. Almost all of the hydro ni um ions would come from the ionization of hydrochloric acid and the hydro ni um ions from hydrochloric acid would suppress the ionization of citric acid. So the first proton of citric acid will not get neutralized with sodium hydroxide until all of the protons from hydrodynamic acid are neutralized by sodium hydroxide. So this means that hydrochloric acid is 100% neutralized at our first equivalence point, and this is going to be our final answer. Now, I hope that made sense and let us know if you have any questions.