Chemistry Halide Ions

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Reactivity of Halide Ions
Purpose:
There are four halide salts used in this experiment that are found in the human body. Sodium fluoride is poisonous, but has been traced to be beneficial to humans in the prevention of tooth decay. Sodium chloride is added to many of our foods to increase flavor. Sodium chloride is important for many life processes, but too much intake is linked to high blood pressure. Sodium bromide is distributed throughout body tissues. Sodium iodine controls cell growth. The principal oxidation number of the halogens is -1. All halogens, except fluorine have other oxidation numbers. In this experiment the production of recognizable precipitates and complex ions will be found. Observations will be used to determine the halide ion presented in the unknown solution. Hypothesis:

If the halide ions react, then the production of precipitate and complex ions will be recognizable. Materials:
*
* 24-well microplate
* AgNO3, 0.1 M
* Ca(NO3)2, 0.5 M
* Gloves
* KBr, 0.2 M
* KI, 0.2 M
* Lab apron
* Na2S2O3, 0.2 M
* NaCl, 0.1 M
* NaF, 0.1 M
* NaOCl (commercial bleach), 5%
* NH3(aq), 4 M
* Safety goggles
* Starch solution, 3%
* Thin-stemmed pipets (12)
Procedure:
1.) Put on safety goggles, gloves, and a lab apron.
2.) Put 4 drops of 0.1 M NaF into each of four wells in the 1st row. Put 4 drops of 0.1 M NaCl into each of the four wells in the 2nd row. Put 4 drops of 0.2 M KBr into each of the four wells in the 3rd row. Put 4 drops of 0.2 M KI into each of the four wells in the 4th row. Put 4 drops of the single unknown solution into each of the four wells in the 5th row. Put 4 drops of the double unknown solution into each of the four wells in the 6th row. 3.) Add 4 drops of 0.5 M Ca(NO3)2 solution to each of the four halide solutions in column 1. Add 4 drops of 0.1 M AgNO3 solution to each of the four halide solutions in column 2. Add 4 drops of 0.1 M AgNO3 + 4 M NH3 solution...
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