I am conducting an experiment on “sunset yellow (FCF)”.
Based on my observations, the substance, when in powder form, is bright red in colour (observed with naked eyes). When I dissolve the powder in distilled water, the solution turns dark red. And the increase in colour intensity is significant.
I am not sure about the reason behind this phenomenon. It is said that FCF can act as a pH indicator through showing different colours. I shall point out that the “water” is distilled and thus should be neutral in nature. My guess is that pH is not a factor leading to this.