Chapter 18, Problem 18.21P

(a)

Interpretation Introduction

Interpretation:

Molar absorptivity of compound A at $\text{238 nm}$ has to be calculated.

Concept Introduction:

Molar absorptivity is a coefficient that appears in Beer’s. It measures the extent of light absorbed at a certain wavelength. Molar absorptivity is denoted by the symbol $\epsilon$. SI unit for molar absorptivity is ${\text{M}}^{-1}{\text{cm}}^{-1}$.

Expression to compute absorbance as per Beer’s law is as follows:

  $A=\epsilon \cdot b\cdot c$

Here,

$\epsilon$ denotes molar absorptivity of species capable to absorb in ${\text{M}}^{-1}{\text{cm}}^{-1}$.

$b$ denotes path length in centimeters.

$c$ denotes concentration or molarity of species capable to absorb.

$A$ denotes absorbance.

$T$ denotes transmittance.

(b)

Interpretation Introduction

Interpretation:

Beer's law has to be used to determine concentration of unknown solution of compound A.

Concept Introduction:

Refer to part (a).

(c)

Interpretation Introduction

Interpretation:

Concentration of A in $\text{25 mL}$ sample solution has to be calculated.

Concept Introduction:

Refer to part (a).

(d)

Interpretation Introduction

Interpretation:

Concentration of A in $\text{2 mL}$ solution has to be calculated.

Concept Introduction:

Refer to part (a).