A solution of sodium hydroxide has a concentration of (2.1 x 10^-1)mol/L. What colour does the solution turn when a few drops of indigo carmine are added?
The solution will be will be yellow.
What is the pH?
What colour is the indicator?
Indigo carmine is blue at pH 11.4 and yellow at pH 13.0.
Since pH > 13.0, the indicator will be