Question

A student created the following Beer's Law Plot by sampling different concentrations of Copper (II) Sulfate solutions and measuring their absorbance at $600nm$ on a spectrophotometer.
What does the slope represent?

• A. The change in absorbance over time $\left(\frac{△A}{time}\right)$.
• B. The change in concentration over time $\left(\frac{△c}{time}\right)$.
• C. The product of the proportionality constant $\left(ϵ\right)$ and the path length $\left(b\right)$.
• D. The product of the absorbance $\left(A\right)$ and the concentration $\left(c\right)$.

Answer 1

Answer: (C)

The product of the proportionality constant $\left(ϵ\right)$ and the path length $\left(b\right)$.

Bar's law is absorbance$=\epsilon \times concentration\times path$

Hence, Slope$=$product of proportionality constant $\left(\epsilon \right)$ and path length $\left(b\right).$