Chapter 18, Problem 18.28P

(a)

Interpretation Introduction

Interpretation:

Value of molar absorptivity has to be calculated.

Concept Introduction:

Molar absorptivity is a coefficient that appears in Beers’ law. 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:

Concentration of ammonia in step 2 has to be calculated.

Concept Introduction:

Refer to part (a).

(c)

Interpretation Introduction

Interpretation:

Concentration of ammonia in $\text{100 mL}$ solution has to be calculated.

Concept Introduction:

Dilution formula is given as follows:

  $M_1{V}_1=M_2{V}_2$

Here,

$M_1$ denotes molarity of concentrated solution.

$V_1$ denotes volume of concentrated solution.

$M_2$ denotes molarity of diluted solution.

$V_2$ denotes volume of diluted solution.

(d)

Interpretation Introduction

Interpretation:

Weight percent of nitrogen in protein has to be calculated.

Concept Introduction:

Refer to part (a).