Question

A Beer's law plot for Cu2+ was experimentally obtained. The slope of the Beer's law plot was 310 L/mol (with a y-intercept = 0.001). A Cu2+ solution of unknown concentration had an absorbance of 0.55. What is the molar concentration of Cu2+ in the unknown solution?

Answer 1

Answer:

$1.7742\times 10^{-3} mol/L$ is the molar concentration of Cu(II) ions in the unknown solution.

Explanation:

Using Beer-Lambert's law :

Formula used :

$A=\epsilon \times C\times l$

where,

A = absorbance of solution

C = concentration of solution

l = length of the cell =

$\epsilon$ = molar absorptivity of solution

A Beer's law plot is between absorbance and concentration.

$\frac{A}{c}=Slope(m)=\epsilon\times l$

We have:

A = 0.55

The slope of the Beer's law plot = m = 310 L/mol

So, the concentration of the solution is:

$c=\frac{A}{m}=\frac{0.55}{310 L/mol}=1.7742\times 10^{-3} mol/L$

$1.7742\times 10^{-3} mol/L$ is the molar concentration of Cu(II) ions in the unknown solution.