Methyl orange, HMO, is a common acid-base indicator. In solution it ionizes
according to the equation: (EQUATION CAN'T COPY) If methyl orange is added to
distilled water, the solution turns yellow. If a drop or two of \(6 \mathrm{M}\)
HCl is added to the yellow solution, it turns red. If to that solution one
adds a few drops of \(6 \mathrm{M} \mathrm{NaOH}\) the color reverts to yellow.
a. Why does adding \(6 \mathrm{M}\) HCl to the yellow solution of methyl orange
tend to cause the color to change
to red? (Note that in solution HCl exists as \(\mathrm{H}^{+}\) and
\(\mathrm{Cl}^{-}\) ions.)
b. Why does adding \(6 \mathrm{M}\) NaOH to the red solution tend to make it
turn back to yellow? (Note that in solution NaOH exists as Na' and OH- ions.
How does increasing [OH-] shift Reaction 3 in the discussion section? How
would the resulting change in \(\left[\mathrm{H}^{+}\right]\) affect the
dissociation reaction of HMO?)
