# Thymol Blue - molar absorptivity

I did a lab about spectrophotometry and right now I need the molar absorptivity(ε) of thymol blue in acidic solution and also in basic solution. I have tried looking online but I haven't found the data I need.

What is the molar absorptivity of thymol blue in acidic solution and in basic solution? information The specific wavelength is 540.27 nm for the acid and 601.88 nm for the base.

• Are you certain that the purpose of the lab was not to find the molar absorptivity by plotting absorbance as a function of concentration of thymol blue in both acid and base? The slope of that line will be the molar absorptivity times the path length: \begin{align} Abs&=\epsilon \ell c\\ y&=mx+b \\ m&=\epsilon \ell\end{align} – Ben Norris May 19 '15 at 1:53
• that is exactly what I did and I have my own results but now I need to calculate the percent error . – ems May 20 '15 at 16:24