# (a) Interpretation: The Ca 2+ concentration in the inner solution of electrode 2 should be determined. Concept introduction: Nernst equation gives the cell potential under non-standard conditions. E = E 0 − 2.303 R T n F log Q E − cell potential E 0 − standard cell potential R − universal gas constant T − temperature in Kelvin n − number of electrons transferred F − Faraday constant Q − Reaction quotient E c e l l = E c a t h o d e 0 − E a n o d e 0 ### Principles of Instrumental Analysis

7th Edition
Douglas A. Skoog + 2 others
Publisher: Cengage Learning
ISBN: 9781305577213 ### Principles of Instrumental Analysis

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

#### Solutions

Chapter 23, Problem 23.27QAP
Interpretation Introduction

## (a)Interpretation:The Ca2+ concentration in the inner solution of electrode 2 should be determined.Concept introduction:Nernst equation gives the cell potential under non-standard conditions.E=E0−2.303RTnFlogQE − cell potentialE0 − standard cell potentialR − universal gas constantT − temperature in Kelvinn − number of electrons transferredF − Faraday constantQ − Reaction quotientEcell=Ecathode0−Eanode0

Interpretation Introduction

### (b)Interpretation:The ionic strength of the solution in Electrode 2 should be determined.Concept introduction:The ionic strength can be calculated as follows:μ=12(c1Z12+c2Z22+c3Z32+....)Here,µ − ionic strengthc − molar concentrations of the ionsZ − charge on the ion.

Interpretation Introduction

### (c)Interpretation:The activity of Ca2+ in electrode 2 should be determined.Concept introduction:The activity of coefficient of species A can be calculated as follows:−logγA=0.509ZA2μ1+3.28αAμHere,γA= activity coefficient of species AZA=Charge on the species Aμ = ionic strength of the solutionαA= the effective diameter of the hydrated ion in nanometers

Interpretation Introduction

### (d)Interpretation:The cell potential versus the pCa should be plotted and pCa value where the plot deviated more than 5% from linearity should be determined. For the linear portion, the slope and the intercept should be determined.Concept introduction:For cations,Ecell=K−0.0592npXHere,K − constantn − number of moles of electronsX − activity of the cation.

Interpretation Introduction

### (e)Interpretation:The cell potential versus the pCa should be plotted for electrode 2 and the range of linearity should be determined. For the linear portion, the slope and the intercept should be determined.Concept introduction:For cations,Ecell=K−0.0592npXHere,K − constantn − number of moles of electronsX − activity of the cation.

Interpretation Introduction

### (f)Interpretation:The reason for the term super-Nernstianto be used for electrode 2 should be discussed.Concept introduction:Electrode 2 has an inner solution with low activities of Ca2+.

Interpretation Introduction

### (g)Interpretation:The cell potential versus the pCa should be plotted and the range of linearity should be determined. For the linear portion, the slope and the intercept should be determined.Concept introduction:For cations,Ecell=K−0.0592npXHere,K − constantn − number of moles of electronsX − activity of the cation.

Interpretation Introduction

### (h)Interpretation:Electrode 3 is said to have Ca2+ release. This term should be explained.Concept introduction:Electrode 3 has an inner solution with higher activities of Ca2+.

Interpretation Introduction

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