Re-write the chemical reactions for both methyl orange and phenolphthalein indic
ID: 499088 • Letter: R
Question
Re-write the chemical reactions for both methyl orange and phenolphthalein indicators. Label the colors expected for both methyl orange and phenolphthalein indicators in their acidic and conjugate base forms. You may refer to the experimental procedure. Hln(aq) + H_2O_ doubleheadarrow H_3O^+ + ln^- (aq) (Orange red, weak acid) (Orange-yellow, conjugate base) H-phph_(aq) + H_2O_(I) doubleheadarrow H_3O^+ + phph^-_(aq) (Colorless, weak acid) (Bright pink, conjugate base) Data Table #2 Using equation 3 (page 37), interpret your observations in terms of lessthanorequalto Chatelier's principle when you added hydrochloric acid to the test tube containing water and methyl orange.Explanation / Answer
According to LeChatellier's principle any change in the system parameter at equilibrium will shift the equilibrium in that direction so as to minimize the change.
Methyl orange (IN-) is yellow
When HCl is added, it gets protonated to form undissociated HIn which is or orange-red in color
When NaOH is added, HIn reacts with it to form more In-, so the solution would turn yello
Phenolphthalein,
starts with pink for phph-
when HCl is added, the phph- anion reacts with added acid to form undissociated Hphph which is clear (colorless)
When NaOH is added, Hphph reacts with base to form phph- anion, which gives a pink coloration to the solution.
The results are thus, acccording to LeChatellier's principle.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.