Liesegang Rings Experiment

Session 2010/2011
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Contents

Introduction 2

Abstract 2

The Chemistry behind Liesegang Rings 3

Safety considerations 4

Procedure 1a 5

Results 6

Analyses 7

Procedure 1b 8

Results 10

Analyses 12

Procedure 1c 13

Results 14

Analyses 14

Procedure 2 Varying the Concentration of Gelatine 15

Results 16

Analyses 18

Procedure 3a 19

Results 21

Analyses 22

Procedure 3b 23

Results 25

Analyses 26

Overall Conclusions 29

References 30

Acknowledgements 31
Introduction

Abstract

Aims:

• To investigate the formation of Liesegang rings in different precipitation reactions in order to get a reliable system of producing the rings. • To investigate the effect of passing a D.C. current through the gel solution on the production of Liesegang rings.

Main findings

• The lead nitrate/potassium iodide and cobalt chloride/ammonium hydroxide reactions both formed bifurcations. The cobalt chloride/ammonium hydroxide reaction was then investigated under different conditions until discernable Liesegang rings had formed. • It was found that the rate of diffusion of ions was increased when a D.C. current was passed through the gel, however the placement of the positive electrode had a dramatic effect on band formation. Band dissolution occurred when the electrode was placed at the top, and closer, more defined bands occurred when it was placed at the bottom.

The Chemistry behind Liesegang Rings

Liesegang rings are a phenomenon which was first observed by the

References: • http://oas.uco.edu/06/paper/weaver.pdf • Nicholls, D (1974) Inorganic Complexes, Dah Hua Printing Press Co, Hong Kong, p • Basolo F, Johnson R (1964) Coordination Chemistry, W. A. Benjamin, Inc., United States of America, p92, • Advanced Higher Chemistry Investigation: Liesegang Rings – Craig Aspell