Question #1f142
1 Answer
An indicator is a weak acid or a weak base that has different colors in undissociated and dissociated states.
In your case, methyl orange is a weak acid that's red in solutions that have a pH lower than 3.1 and yellow in solutions that have a pH larger than 4.4.
Because hydrochloric acid is a strong acid, it will dissociate completely to form
This means that the concentration of the
Now, the generic equilibrium reaction for methyl orange (or any weak acid indicator, for that matter) is
The equilibrium constant is defined as
Use the pKa value given for methyl orange to determine the value of
Since you know
This is how much of the methyl orange will be left in basic form (yellow)
This means that the acid form (red) will be
Because the pH of the solution is very low
almost all of the methyl orange will be in acidic form.