Exp:51: Determination of Iodine in Salt - PowerPoint PPT Presentation

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Exp:51: Determination of Iodine in Salt

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The main purpose of this experiment was to determine the iodine in salt using ... into an electrical potential which can be measured by a voltmeter or pH meter. ... – PowerPoint PPT presentation

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Title: Exp:51: Determination of Iodine in Salt


1
Exp5-1 Determination of Iodine in Salt
  • By
  • Vaidehi Desai

2
Purpose
  • The main purpose of this experiment was to
    determine the iodine in salt using the
    ion-selective electrode.
  • Ion-selective electrode were used in the
    experiment because they respond selectively to
    one ion.
  • The ion-selective electrode does not depend on
    the oxidation-reduction reactions. Rather, it
    depends on the migration of the selected ions
    across the membrane

3
ION SELECTIVE ELECTROD
  • An Ion-selective electrode (ISE) is sensor which
    converts the activity of a specific ion dissolved
    in a solution into an electrical potential which
    can be measured by a voltmeter or pH meter. The
    voltage is theoretically dependent on the
    logarithm of the ionic activity. The sensing part
    of the electrode is usually made as an
    ion-specific membrane, along with a reference
    electrode.

4
How do ISE work?
  • An Ion Selective Electrode measures the potential
    of a specific ion in solution. This potential is
    measured against a stable reference electrode of
    constant potential. The potential difference
    between the two electrodes will depend upon the
    activity of the specific ion in solution. This
    activity is related to the concentration of that
    specific ion, therefore allowing the end-user to
    make an analytical measurement of that specific
    ion.

5
Equations
  • There were two main equations used in this lab.
  • Ecell K ((.05916)/n))log a
  • According to the above equation, the measure cell
    potential for an electrochemical cell containing
    an ISE is related to the activity of the selected
    ion.

6
Equations
  • The second equation is
  • X S(.091/A-.909).
  • The above equation is the standard addition
    method. It is used in the experiment because it
    compensate for any matrix effect and it minimizes
    the problems with the electrode drift.
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