Alkaline Earths

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The Alkaline Earths and the Halogens-Two Families in the Periodic Table

Objective:

The purpose of this experiment is to study the properties of the elements in two families in the Periodic Table, the Alkaline Earths and the Halogens. I will also mix solutions of halogens and halide ions to determine the relative oxidizing strengths of the halogens.

Introduction:

The alkaline Earths are all reactive metals and include barium, beryllium, calcium, magnesium, radium, and strontium. The halogens are also relatively reactive. They include astatine, bromine, chlorine, fluorine, and iodine. The halogens are molecular substances and oxidizing agents, and all have odors. They are only slightly soluble in water and are much more soluble in HEX, where they have distinct colors. The halide ions exist in solution only in water, have no color or odor, and are not oxidizing agents. They do not dissolve in HEX.

Data:

l. Solubilities of Salts of the Alkaline Earths

• Ba(No3)2 mixed with 1 M H2SO4 = No precipitate forms.

• Ba(No3)2 mixed with 1 M Na2CO3= No precipitate forms.

• Ba(No3)2 mixed with 0.25 M (NH4)2C2O4= A little precipitate forms.

• Ba(No3)2 mixed with 0.1 M KIO3= No precipitate forms.

• Ca(NO3)2 mixed with 1 M H2SO4= No precipitate forms.

• Ca(NO3)2 mixed with 1 M Na2CO3= Precipitate forms.

• Ca(NO3)2 mixed with 0.25 M (NH4)2C2O4= Precipitate forms.

• Ca(No3)2 mixed with 0.1 M KIO3= No precipitate forms.

• Mg(No3)2 mixed with 1 M H2SO4=No precipitate forms.

• Mg(No3)2 mixed with 1 M Na2CO3= Precipitate forms.

• Mg(No3)2 mixed with 0.25 M (NH4)2C2O4= No precipitate forms.

• Mg(No3)2 mixed with 0.1 M KIO3= No precipitate forms.

• Sr(NO3)2 mixed with 1 M H2SO4 = Precipitate forms.

• Sr(NO3)2 mixed with 1 M Na2CO3= Precipitate forms.

• Sr(NO3)2 mixed with 0.25 M (NH4)2C2O4= Precipitate forms.

• Sr(NO3)2 mixed with 0.1 M KIO3= No precipitate forms.

II. Relative Oxidizing Powers of the Halogens

a) Color of the halogen in solution:

HEX:

Br2=Yellow to orange.

Cl2=Clear to white cloudy.

I2=Orange to light pink top with yellow on the bottom.

WATER:

Br2=Clear to clear.

Cl2=Clear to foam.

I2=Orange to orange.

b) Reactions between halogens and halides:

• Br2 mixed with Br-= No reaction.

• Cl2 mixed with Br-=No reaction. (Top layer foam)

• I2 mixed with Br-=No reaction.

• Br2 mixed with Cl-=No reaction.

• Cl2 mixed with Cl-=No reaction. (Foam)

• I2 mixed with Cl-=No reaction.

• Br2 mixed with I-=Reaction occurs. HEX layer. (yellow on top amber on bottom)

• Cl2 mixed with I-= Reaction occurs. Clear to yellow to layers with foam.

• I2 mixed with I-=No reaction occurs.

Experiment:

I. Relative Solubilities of some salts of the alkaline earths:

• To each of four small test tubes I added about 1 mL of 1M H4SO4.

• Then I added 1 mL of 0.1 M solutions of the nitrate salts of barium, calcium, magnesium, and strontium to those tube, one solution to a tube.

• I stirred each mixture with glass stirring rod.

• Noted if any precipitate forms or characteristics change.

• I then rinsed out each of the test tubes, and to each I then added 1 mL 1M Na2CO3-.

• Then added 1 mL of the solutions of the alkaline earth salts, one solution to a test tube, as before.

• Recorded my observations.

• Rinsed out the test tubes, and test for solubilities of the oxalates of these cations, using 0.25 M (NH4)2C2O4 as the precipitating agent.

• Finally, I determined the relative solubilities of the iodates of the alkaline earths, using 1mL 0.1 M KIO3 as the test reagent.

II. Relative oxidizing powers of the halogens:

• In a small test tube I placed a few milliliters of bromine-saturated water and added 1 mL of hexane....
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