I have a titration to determine the sodium carbonate content in a zinc plating solution. After performing the titration, the specified color changes were not seen. The procedure is as follows:
1. Pipette a 5ml sample of operating solution into a 250ml Erlenmeyer flask.
2. Add 100ml DI water
3. Add 0.5g indigo carmine indicator
4. Titrate with 0.94N sulfuric acid to a yellow-green endpoint.
5. Rezero the burette.
6. Add 5 drops of methyl orange indicator.
7. Titrate with 0.94N sulfuric acid to a gray-purple endpoint.
8. Add ~0.5g of indigo carmine indicator.
9. Titrate with 0.94N sulfuric acid to a blue endpoint.
When performing the titration, I never saw the yellow-green color shift. The solution went from orange-brown to a blue. If anyone has any advice or recommendations, they would be greatly appreciated. Thank you in advance.