Question

1 pH mL NaOH Phosphoric Acid w/ NaOH 1.76 1.93 2.08 2.27 2.34 2.45 2.61 2.82 3.01 3.13 3.33 3.55 3.79 4.17 5.02 5.22 5.43 205.59 5.68 5.82 6.05 6.26 6.35 6.13 6.51 6.62 9.9 10.8 11.6 12.2 12.5 12.9 13.1 13.3 13.4 13.7 13.8 14 14.2 10 12 13 14. 15 16 19 6 21 14.8 15.4 16.1 16.7 17.2 17.7 18.5 23 24 27 28 6.77 6.9 7.03 7.17 7.34 7.13 7.53 7.7 30 31 32 19.5 20.5 1.5 22.5 23.5 21 24.5 25.1 25.4 25.7 25.9 26.6 26.7 35 37 39 41 19 2021 26 2 7.89 8.02 8.91 9.06 9.72 9.68 9.85 10.03 10.15 10.5 10.84 11.03 mL of NaOH added 43 27 27.1 27.3 27.5 28 29 45 46 48 50

Titration between phosphoric acid and NaOH.

For Ka1, calculate: 1/2 equivalence point, equivalence point, and after 7.5 mL added.

For Ka2, calculate: 1/2 equivalence point, equivalence point, and after 17.5 mL added.

Please show step by step, thank you!

Answer 1

1) The first point of equivalence is observed in the first jump of pH at 13.5 mL about 4.5 pH.

The mean point of equivalence is determined at the average volume, which is 6.75 mL, a pH of 2 is read.

At 7.5 mL a pH of 2.1 is read.

2) The second equivalence point is observed at 26.5 mL, with a pH of 9.

The second mean point of equivalence is observed at 20.2 mL, with a pH of 6.8.

At 17.5 mL a pH of 6.5 is read.

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