ACADEMIC CHEMISTRY
PERIOD:
ACTIVITY OF ALKALINE EARTH METALS
NAME:
DATE:
INTRODUCTION
In this lab we will be investigating some chemical and physical properties of the alkaline earth metals. The alkaline earth metals are members of group IIA on the periodic table. The alkaline earth metals are quite reactive, yet not as reactive as the alkali metals (group IA). Alkaline metals also tend to have higher melting and boiling points and are much more dense and hard when compared to the alkali metals.
In procedure I, you will investigate the reaction of the alkaline metals with water.
The metallic character of an element is defined by its tendency to lose or donate electrons in a chemical reaction. Since metal reactivity increases as you go down a family, metallic character also increases. Recall that the energy needed to remove an electron from an atom is called ionization energy. The lower the ionization energy, the easier it is for the metal to donate electrons and the more reactive it is. More metallic elements are more likely to react with water. We will test the reactions of calcium and magnesium with water as in the following reactions:
Ca (s) + 2 H
2
O (l)  Ca(OH)
2
(s) + H
2
(g)
Mg (s) + 2 H
2
O (l)  Mg(OH)
2
(s) + H
2
(g)
As metallic character increases, the tendency of the elements to form ions also increases. As you move down the group, the solubility of the metal hydroxide compounds (include OH -1 ) formed by the elements in group IIA increases. That is, they become more likely to dissolve in water. The more active the metal, the more basic the solution will become when the metal is dissolved. The most active metals will form solutions with high pH. This trend will be observed in procedure II.
Procedure III will test the solubility of alkaline earth compounds. The sulfate
(containing SO
4
-2 ) compounds of group II show decreasing solubility as you move down the group. This characteristic is used as a means of separating and identifying metallic ions of this group.
Procedure IV will test the solubility of alkaline earth compounds that contain carbonate (CO
3
-2 ). Group IIA metal carbonate compounds are quite insoluble and do not dissolve well in water. The solubility of metal carbonates decreases as you move down the group.
The final procedure, V, will use a flame test to identify the alkaline metal. Each metal has a distinguishable color flame caused by the excitation of the metal’s electrons. The energy from the flame excited the electrons to higher energy levels.
When the electrons return to lower energy level, light is emitted and a discrete line spectrum can be observed. This line spectrum is unique for each metal and may be used to identify them.
PRELAB
1. What is the group number in which the alkaline earth metals are found?
2. Define metallic character.
3. Define solubility.
4. Show the trends for solubility of group IIA metal hydroxides, group IIA metal sulfates, and group IIA metal carbonates as you go down the group.
5. Why must you use care when handling the hydroxide solutions?
6. What direction should the flaming splint and test tube be pointed when performing the hydrogen test?
7. Match the name of the compound with its chemical formula. Include the letter and the formula in your answer.

ACADEMIC CHEMISTRY
PERIOD: a. Magnesium b. Calcium c. Calcium hydroxide d. Strontium nitrate e. Calcium chloride f. Magnesium hydroxide g. Calcium sulfate h. Magnesium chloride i. Strontium hydroxide j. Magnesium sulfate k. Sodium carbonate
Ca
Mg
MgSO
4
CaSO
4
Sr(NO
3
)
Ca(OH)
2
Mg(OH)
2
Sr(OH)
2
Na
2
CO
3
MgCl
2
CaCl
2
NAME:
DATE:
OBJECTIVES
The objective of this experiment is to observe the similarities and differences in the chemical and physical properties of the alkaline earth metals.
MATERIALS
Ca turnings
Mg ribbon
Magnesium sulfate (s)
Calcium sulfate (s)
0.1 M calcium chloride (aq)
Calcium chloride crystals (s)
Bunsen burner
Wooden splints
Strontium nitrate (s)
Strontium hydroxide saturated solution
Magnesium hydroxide saturated solution
Phenolphthalein solution
0.1 M sodium carbonate (aq)
0.1 M magnesium chloride (aq)
PROCEDURE matches
PH paper
Test tubes
Test tube rack
Stirring rod
Crucible tongs
PROCEDURE I:
Reactivity of alkaline earth metals
1. Pour about 5 ml of distilled water into a clean, dry test tube and place the tube in a test tube rack. Add a calcium turning to the tube. To collect the gas being produced, invert a test tube over the first one. Use a test tube clamp placed in the center of the tube used to collect the gas.
2. After collecting the gas for a minute or two, insert a flaming splint into the test tube that collected the gas. Make sure the test tube is pointed away from your face when doing this test for hydrogen. A “bark” will be heard if H
2
(g) is present.
3. Add a few drops of phenolphthalein solution to the test tube containing the solution.
Make observations and record in your data table.
4. Repeat the steps with a ½ cm piece of magnesium ribbon.
5. Pour off liquids from test tubes, dispose of solids in the trash and wash test tubes with a test tube brush.

ACADEMIC CHEMISTRY
PERIOD:
PROCEDURE II:
NAME:
DATE:
PH of Alkaline earth metal hydroxides
1. Obtain 3 strips of pH paper.
2. Use a dropper pipet to apply a few drops of solution to the paper and record the pH value in your data table. Test calcium hydroxide, magnesium hydroxide, and strontium hydroxide.
3. Throw used pH strips in the trash and clean up any excess solution.
PROCEDURE III:
Relative solubility of alkaline earth metal compounds containing sulfate
1. Measure a 0.5 gram sample of magnesium sulfate and place it in a clean, dry test tube. Measure a 0.5 gram sample of calcium sulfate and place it in a clean, dry test tube.
2. Add approximately 5 ml of distilled water to each tube. Using a stirring rod, mix each solution thoroughly, getting as much of the solid to dissolve as possible.
Record your observations in your data table.
3. Clean the tubes with a test tube brush.
PROCEDURE IV:
Formation of carbonate compounds by alkaline earth metals
1. Place two clean, dry test tubes in the test tube rack. Add about 2 ml of each 0.1 M solution (magnesium chloride (aq), and calcium chloride (aq)) to the test tubes.
2. Add 1 ml of 0.1M sodium carbonate solution to each test tube and record your observations in the data table.
3. pour liquid from test tubes, dispose of solids in the trash, and wash test tubes using a test tube brush.
PROCEDURE V:
Flame tests of the alkaline earth metals
1. obtain wet wooden splints and a small piece of magnesium ribbon (1 cm or less).
2. light your Bunsen burner.
3. dip the wet splint into the strontium nitrate crystals and place it into the flame.
Record your observations. Dip the wet splint into the calcium chloride crystals and place it into the flame. Record your observations.
4. use crucible tongs to hold a small piece of magnesium metal in the flame. Do not look directly at the flame. Record your observations.
5. Dispose of used splints in the trash. Wipe any salt from the table.

ACADEMIC CHEMISTRY
PERIOD:
DATA
Observations
Test for hydrogen gas
Result of adding phenolphthlein
PH value
Mg(OH)
2
Ca(OH)
2
Ca and H
2
O
Sr(OH)
2
Magnesium sulfate
Calcium sulfate
NAME:
DATE:
Mg and H
Observations of solubility
2
O
Reaction
Magnesium chloride and sodium carbonate
Calcium chloride and sodium carbonate
Metal Ion
Ca +2
Observations
Mg +2
Flame color
Sr +2

ACADEMIC CHEMISTRY
PERIOD:
SUMMARY
NAME:
DATE:
Discuss the most dramatic qualitative observations made in lab and the metal(s) responsible for those observations. Summarize the reactivity of the alkaline earth metals tested during the lab. Relate their activity to the position of the metal on the periodic table.
POST LAB QUESTIONS
1. For procedure I, which is more reactive, calcium or magnesium? Explain using observations from the lab.
2. For procedure I, describe the reactivity trend of the metals in family two as you move down the periodic table.
3. For procedure II, is there a relationship between the pH of the alkaline earth metal hydroxides and the location on the table? Explain.
4. For procedure II, which compound is most basic?
5. For procedure III, is there a relationship between the solubility of alkaline earth metal sulfates and the location on the periodic table? Explain.
6. For procedure IV, is there a relationship between solubility of alkaline earth carbonates and the location on the periodic table? Explain.
7. For procedure V, how can calcium, magnesium and strontium be distinguished from each other?
8. Describe the similarities and differences between the chemical and physical properties of the elements of group IIA. List 3 similarities and 3 differences.
9. Why does metallic character of alkaline earth metals increase as you move down the group? Discuss in terms of electron configuration, ionization energy, atomic radius, etc.