andrevil45
Answered

Discover answers to your most pressing questions at Westonci.ca, the ultimate Q&A platform that connects you with expert solutions. Join our Q&A platform and connect with professionals ready to provide precise answers to your questions in various areas. Get precise and detailed answers to your questions from a knowledgeable community of experts on our Q&A platform.

2) Phenolphthalein (C20H1404) is a dye very commonly used as indicator in acid-base titrations. The simplified
generic expression for the dissociation of this molecule in water is shown in the equation below, where Hin
represents the phenolphthalein molecule and In is the phenolphthalein ion. Their appearance and relevant
properties are also shown below.
HIn (S) + H20 (1) = H30* (aq) + In" (aq)
a. Can this equilibrium be controlled by changing the pH of the solution? Briefly explain.
b. What color do you expect to see in the solution when you add acid to it? Briefly explain.

Sagot :

abibatibrahim11

Answer:

methyl orange is an indicator

The pKa of phenolphthalein is 9.3.

Who discovered phenolphthalein?

By combining phenol and phthalic anhydride in the presence of sulfuric acid or zinc chloride, German chemist Adolf von Baeyer created phenolphthalein in 1871.

What is phenolphthalein?

It is a weak acid that is colorless. Its base due to loss of proton ,[tex]C_{20} H_{13} O_{4}^{-}[/tex] is an intense shade of pinkish-red.

What is the molecular formula of phenolphthalein?

The molecular formula is C₂₀H₁₄O₄.

What is the structure of phenolphthalein?

  • Three hexagonal structures, one pentagonal structure, two alcoholic groups, and one ketone group make up the structure of phenolphthalein.
  • Aside from that, the carbon, hydrogen, and oxygen chains make up the structure of phenolphthalein.

What is the equation at equilibrium?

The equation is:

[tex]HIn +H2O----- > In^{-} +H3O^{+}[/tex]

Can the equilibrium change with change is pH?

  • If [tex]H_{3} O^{+}[/tex] is introduced (acidic solution), the equilibrium will be moved to the left.
  • Thus, in a very acidic solution, almost all of the pink [tex]In^{-}[/tex] will be converted into colorless [tex]HIn[/tex].
  • On the other hand, if the solution is made extremely basic, [tex]OH^{-}[/tex] ions will react with  [tex]HIn[/tex] molecules and change them into  [tex]In^{-}[/tex] , which will cause the equilibrium to shift to the right.
  • The phenolphthalein solution will turn pink as a result.

What color do you expect to see in the solution when you add acid to it?

  • When acid is added to the solution containing the indicator the color of the solution will begin to decrease in intensity.
  • It is because If [tex]H_{3} O^{+}[/tex] is introduced (acidic solution), the equilibrium will be moved to the left.
  • Thus, in a very acidic solution, almost all of the pink [tex]In^{-}[/tex] will be converted into colorless [tex]HIn[/tex].

To learn more about phenolphthalein, acidic solution and weak acid here,

https://brainly.com/question/14804470

#SPJ3

We hope this was helpful. Please come back whenever you need more information or answers to your queries. We hope our answers were useful. Return anytime for more information and answers to any other questions you have. Thank you for visiting Westonci.ca. Stay informed by coming back for more detailed answers.