Solutions of acridine ( 11.9) in ethanol absorb at λ=250 nm(logε=5.3) . (a) What is the concentr

step 1 Okay, so there are two questions about this problem. This question is about the compound given h

Solutions of acridine ( 11.9) in ethanol absorb at λ=250...

Solutions of acridine ( $11.9)$ in ethanol absorb at $\lambda=250 \mathrm{nm}(\log \varepsilon=5.3) .$ (a) What is the concentration of acridine in a solution within a cell of path length $0.50 \mathrm{cm}$ for which the absorbance is $0.96 ?$ (b) What mass of acridine is required to prepare $250 \mathrm{cm}^{3}$ of this solution? CAN'T COPY THE FIGURE CAN'T COPY THE GRAPH

Solutions of acridine ( $11.9)$ in ethanol absorb at $\lambda=250 \mathrm{nm}(\log \varepsilon=5.3) .$ (a) What is the
concentration of acridine in a solution within a cell of path length $0.50 \mathrm{cm}$ for which the absorbance is $0.96 ?$ (b) What mass of acridine is required to prepare $250 \mathrm{cm}^{3}$ of this solution?
CAN'T COPY THE FIGURE
CAN'T COPY THE GRAPH

Key Concepts

Molar Extinction Coefficient

The molar extinction coefficient, often represented as log ? or ?, quantifies how strongly a chemical species absorbs light at a given wavelength. It is a crucial parameter in the Beer-Lambert Law that helps correlate the measured absorbance to the concentration of the compound in the solution.

Spectrophotometry

Spectrophotometry is an analytical technique used to measure the amount of light that a chemical substance absorbs by passing a light beam through a sample. The technique is widely used for concentration determination in solutions, leveraging the Beer-Lambert Law to convert absorbance data into quantitative information.

Beer-Lambert Law

The Beer-Lambert Law establishes a linear relationship between the absorbance of a solution and the concentration of the absorbing species, given a specified path length. This concept is foundational in spectrophotometry as it allows for the determination of unknown concentrations by measuring the light absorbance at a specific wavelength.

Unit Conversions and Stoichiometric Calculations

Unit conversions and stoichiometric calculations are essential for translating concentrations obtained from spectrophotometric measurements into practical quantities such as the mass of solute required. This encompasses converting between units (such as centimeters to liters or moles to grams) and using molecular weight as a conversion factor to determine the amount of substance needed for a solution.

Transcript

00:01 Okay, so there are two questions about this problem.

00:06 This question is about the compound given here, which is called the acridine.

00:16 So the first question is what is the concentration of the acetylene in the solution within a cell of pass lens 0 .5 centimeters, for which the adorbents is 0 .96.

00:30 So we know we have to use beer lamber's law to calculate the concentration, right? so let's first write down the beer lamber's law, which is the concentration, no, the absorbance of the solution equals to, right, the extinction coefficients times the concentration, times the passlands.

00:53 And we can do a rearrangement.

00:55 So we know the concentration equals to the absorbens.

01:01 Over the extinction coefficients times the pass lens.

01:08 Now we can plug in numbers.

01:12 The absorbance is given, which is 0 .96 here.

01:19 And the extinction coefficient is 10 to 5 .3, right? and the pass lens here says it's 0 .5.

01:32 And use the calculator, we find the concentration equals to 9 .623 times 10 to minus 6 more per liter, which is a pretty small number.

01:52 So the second question is what mass of the acridine is required to prepare 250 centimeters square of this? this solution.

02:05 So then it's about making the solution, right? so if you remember what's the concentration, how to express the concentration in morse.

02:17 The concentration is actually equals to, right, when you prepare the solution, equals to the morse of the, right, the solubors over the volumes of the solution.

02:39 So then to the arrangements, we know the mores of the solubors is equal to the concentration times the volume.

02:51 And the concentration here is given, right? we calculated is 9 .623 times 10 to minus 6 .6...

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