Question

3. A Beer's law plot for Cu2+ was experimentally obtained. The slope of the Beer's law plot was 435 L/mol (with a y-intercept = 0.001). A Cu2+ solution of unknown concentration had an absorbance of 0.75. What is the molar concentration of Cu2+ in the unknown solution?

Answer 1

Answer:

0.00172 M

Explanation:

According to the Lambert's Beer law:-

$A=\epsilon l c$

Where, A is the absorbance

l is the path length

$\epsilon$ is the molar absorptivity

c is the concentration.

If a graph is plotted between the concentration and absorbance, then the slope is:- $\epsilon l$. So,

$c=\frac{A}{slope}=\frac{0.75}{435}\ M=0.00172\ M$

0.00172 is the molar concentration of $Cu^{2+}$ in the unknown solution.