Certainly! Let's tackle each part of your question step-by-step.
Part 3: Finding the Concentration of the Unknown Solution Using Beer's Law
Beer's Law is a very important principle in chemistry, which states that the absorbance (A) of a solution is directly proportional to the concentration (c) of the solution, given that the path length (l) and molar absorptivity (ε) are constant. The formula is given by:
[tex]\[ A = \varepsilon \cdot l \cdot c \][/tex]
Where:
- [tex]\( A \)[/tex] is the absorbance,
- [tex]\( \varepsilon \)[/tex] is the molar absorptivity,
- [tex]\( l \)[/tex] is the path length,
- [tex]\( c \)[/tex] is the concentration.
Since the solutions are measured under the same conditions, [tex]\(\varepsilon\)[/tex] and [tex]\(l\)[/tex] are constant and can be cancelled out when comparing two solutions.
Given:
- Concentration of known solution ([tex]\( c_1 \)[/tex]) = 0.25 M,
- Absorbance of known solution ([tex]\( A_1 \)[/tex]) = 0.65,
- Absorbance of unknown solution ([tex]\( A_2 \)[/tex]) = 0.45.
We want to find the concentration of the unknown solution ([tex]\( c_2 \)[/tex]).
By the relationship of Beer's Law for two solutions:
[tex]\[ \frac{A_1}{A_2} = \frac{c_1}{c_2} \][/tex]
Rearranging to solve for [tex]\( c_2 \)[/tex]:
[tex]\[ c_2 = c_1 \cdot \frac{A_2}{A_1} \][/tex]
Substituting the known values:
[tex]\[ c_2 = 0.25 \, \text{M} \cdot \frac{0.45}{0.65} \][/tex]
[tex]\[ c_2 \approx 0.17307692307692307 \, \text{M} \][/tex]
So, the concentration of the unknown solution is approximately 0.173 M.
Part 4: Example of a Fluorescent Molecule
An example of a molecule that fluoresces is Fluorescein.
Fluorescein is a widely used fluorescent tracer in many applications, including microscopy, forensics, and medical diagnostics. It is popular for its strong fluorescence and can be excited with different wavelengths, making it a versatile tool in fluorescence-based studies.
So, to summarize:
1. The concentration of the unknown solution is approximately 0.173 M.
2. Fluorescein is a good example of a fluorescent molecule.
