35 Answer the following questions based on EQUL 397 (a) A certain colorless solu

Question

35 Answer the following questions based on EQUL 397 (a) A certain colorless solution has a pH of 10 If we add phenolphthalain indicator to this solution, whar wll be the color of the resuting solution? Explain. i Now, suppess we add an acid drop-wise to the solusen fram 0). What wil be observed as we acd the acid? Expiaih The pH of a certain solution i. ED. What color would th·indicator, mthyl volet, Methyl volet Methyl orage henciphthalein ) The pH of a mechyl orange, and phenolphthalsin be in this solutiont (e) Methyl violet is violet in a given solution, Methyt orange is red in the same solution. What is the approximate pH of the solution? Briely justity your anawwer

Explanation / Answer

1. Phenolphtalein is a chemical compound with the formula C20H14O4 and is often written as "HIn" or "phph" in shorthand notation. Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless inacidic solutions and pink in basic solutions.

Phenolphthalein adopts four different states in aqueous solution: Under very strongly acidic conditions, it exists in protonated form, providing an orange coloration. Under strongly acidic conditions, the lactone form is colorless. The singly deprotonated phenolate form (the anion form of phenol) gives the familiar pink color. In strongly basic solutions, phenolphthalein's pink color undergoes a rather slow fading reaction and becomes completely colorless above 13.0 pH. The rather slow fading reaction that produces the colorless InOH3 ion is sometimes used in classes for the study of reaction kinetics.

So, if this solution with a pH of 10 it's a basic solution, the solution will turn fuchsia, but if it's an acid solution it will remain colorless, until some drops of base are added. However, the pH of 10 so this is an basic solution. It turns fuchsia (or pink).

2. Adding some acid to the solution will cause to the solution to lower it's pH from strong base conditions to acidic conditions, so, the pink color will slowly dissapear until it's colorless once again.

3. For a solution with a pH = 6, the indicators would have these colors:

methyl violet = Violet

Phenolphtalein = colorless

Methy orange = yellow

4. the methyl orange has a pH virage of 3.1 - 4.4. while methyl violet is 0.1 - 1.6. If solution with methyl violet is violet, then this means that the pH is above 1.6. Now if with methyl orange it turns red, this means that is under 4.4 and it's minimum in 3.1 of pH. So the solution would have to be in a pH range of 3 - 4, but no more of 4.4.

Hope this helps.

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