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  • Questions 4-6 pertain to this titration curve A weak monoprotic acid is titrated with a

  • strong base, KOH. A titration curve typically has the volume

  • of the titrant, usually a strong base, on the x axis, and the resulting pH on the y

  • axis. There’s an equivalence point on the graph

  • where all of the starting solution has been neutralized by the titrant. So here we started

  • with an acid, and it’s the point where youve added enough base to neutralize the acid.

  • You can usually eyeball this point - where the concavity of the graph changes .

  • The point at which the moles of the added strong base are equal to the moles of the

  • weak acid initially present.

  • The answer is C, that's what we were just talking about.

  • You can see where the concavity of the graph changes.

  • This is the equivalence point.

  • And you can see on the graph it corresponds with about 100 mL of KOH

  • The point at which the pH is closest to that of the strong base being added

  • This is point E. We are past the equivalence point, where all the acid has been neutralized.

  • Past that point, more and more base is being added, so you can see the pH increasing and

  • increasing, until it starts to level off. You can see it is still changing at point

  • D, so it’s not quite at the pH of the titrant. But by point E, the curve is changing less

  • and is closer to a plateau. So E is the best answer.

  • The point at which the concentrations of the weak acid and its conjugate base are approximately equal.

  • So here you need to know a little detail about titration curves.

  • For monoprotic acids, the point halfway

  • between the start of the curve and the equivalence point is significant - that’s where the

  • concentrations of the acid and its conjugate base are equal. We found the equivalence point

  • was C, when you add 100 mL of KOH. Halfway is 50 mL, which corresponds to point B on

  • the graph.

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Questions 4-6 pertain to this titration curve A weak monoprotic acid is titrated with a

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B2 中高級

化學備考:2008年AP化學4-6題答案及解析 (Chemistry Test Prep: 2008 AP Chemistry Questions 4-6 Answers & Explanations)

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    林宜悉 發佈於 2021 年 01 月 14 日
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