<em>A</em> = <em>ε</em> by the Beer-Lambert law, where
<em>A</em> the absorbance,
the path length,
<em>ε</em> the molar absorptivity of the solute, and
concentration of the solution.
<em>A</em> and <em>ε </em>are the same for both solutions. Therefore, is constant; is inversely proportional to . The 100 mL sample would have a concentration 1/4.78 times that of the 45.0 mL reference.
The 13.0 mL standard solution has a concentration of 5.17 ⨯ M. Diluting it to 45.0 mL results in a concentration of 1.494 M.
is inversely related to for the two solutions. As a result, c₂ = 3.126 M.
The 30.0 mL sample has to be diluted by 30.0 / 100.0 times to produce the 100.0 mL solution being tested. The 100.0 mL solution has a concentration of 3.126 M. Therefore, the 30.0 mL solution has a concentration of 1.04 ⨯ M.