(a) Interpretation: Mass absorption coefficient of a solution containing 11.00 g of KI and 89.00 g of water should be calculated. Concept introduction: Mass absorption coefficient ( μ M ) is the absorption cross section per unit mass (units are cm 2 /g) . Mass absorption coefficient is independent of chemical and physical nature of elements. Mass absorption coefficient ( μ M ) of a sample can be calculated by adding the contributions of the mass absorption coefficients of each element present in the sample. Contribution of “element A” to the mass absorption coefficient of a sample can be written as W A μ A Where, W A = weight fraction of the element A and μ A = mass absorption coefficient of the element Therefore, the mass absorption coefficient ( μ M ) of a sample can be written as, μ M = W A μ A + W B μ B + W C μ C + ... In order to calculate mass fractions of each element in a sample, the atomic mass of each element and the molar mass of each compound should be known. Weight fraction ( W A ) = atomic mass of the element molar mass of the compound × weight of the compound × 1 weight of the sample Atomic/molar masses of K =39 .10 g/mol I =126 .90 g/mol K =39 .10 g/mol H =1 .01 g/mol O =16 .0 g/mol KI =166 .0 g/mol H 2 O =18 .02 g/mol

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Principles of Instrumental Analysis

7th Edition
Douglas A. Skoog + 2 others
Publisher: Cengage Learning
ISBN: 9781305577213
BuyFind

Principles of Instrumental Analysis

7th Edition
Douglas A. Skoog + 2 others
Publisher: Cengage Learning
ISBN: 9781305577213

Solutions

Chapter 12, Problem 12.6QAP
Interpretation Introduction

(a)

Interpretation:

Mass absorption coefficient of a solution containing 11.00 g of KI and 89.00 g of water should be calculated.

Concept introduction:

Mass absorption coefficient ( μM ) is the absorption cross section per unit mass (units are cm2/g). Mass absorption coefficient is independent of chemical and physical nature of elements.

Mass absorption coefficient ( μM ) of a sample can be calculated by adding the contributions of the mass absorption coefficients of each element present in the sample.

Contribution of “element A” to the mass absorption coefficient of a sample can be written as WAμA

Where, WA= weight fraction of the element A and μA=mass absorption coefficient of the element

Therefore, the mass absorption coefficient ( μM ) of a sample can be written as,

μM=WAμA+WBμB+WCμC+...

In order to calculate mass fractions of each element in a sample, the atomic mass of each element and the molar mass of each compound should be known.

Weight fraction (WA) = atomic mass of the elementmolar mass of the compound × weight of the compound×1weight of the sample

Atomic/molar masses of K =39.10 g/molI   =126.90 g/molK  =39.10 g/molH  =1.01 g/molO  =16.0 g/molKI =166.0 g/molH2O  =18.02 g/mol

Interpretation Introduction

(b)

Interpretation:

Transmitted fraction of the radiation when the Mo Kα source radiation is passed through a 0.40 cm layer of the solution should be calculated.

Concept introduction:

Beer’s law can be written as follows, in which, mass absorption coefficient ( μM ) is included.

lnpop=μMρxPo= power of incident beamp= power of transmitted beamρ = density of the samplex= sample thickness in cm

Transmittance (T) of a medium is the fraction of incident radiation transmitted by the medium.

T=PPo

Therefore, transmittance can be rewritten as:

ppo=1eμMρx

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