Title: Reactivity of Alkaline Earth Metals

Title: Reactivity of Alkaline Earth Metals

Purpose: To find how the activities of the alkaline earth metals magnesium and calcium compare to each other and to aluminum.

Materials and Apparatus: safety goggles; lab apron; 3 petri dishes; wax marking pencil; forceps; magnesium ribbon (Mg); calcium metal turnings (Ca); aluminum foil (Al); micropipet; distilled water; micropipet with phenolphthalein solution; steel wool; wash bottle with distilled water; lab burner; striker or matches; crucible tongs; wire gauze square; aluminum oxide (Al2O3); microspatula

Drawings:

Procedures and Observations:

Procedures:

Part A

1.  First, put on the safety goggles and lab apron. Then label three petri dishes and the covers Mg, Ca, and Al, using a marking pencil.

2.  Remove the petri dish covers and rest them on the lab table so that the open side is up. Using the forceps, place the following metal samples in the labeled petri dish covers: a 4-cm piece of Mg ribbon, a small piece of calcium turning, and a piece of aluminum foil about the size of the Mg ribbon. Do not touch the calcium with hands, it is corrosive. Record the appearance of each kind of metal in Data Table 1.

3.  Then place three micropipets of distilled water into each of the petri dishes.

4.  Using the forceps, remove the piece of calcium turning from the lid to the petri dish. Place the cover over the petri dish immediately. Observe the reaction through the plastic cover because the reaction can cause skin irritation. Record the observations.

5.  If a piece of metal does not react, lift the cover at an angle away from you and gently squirt the metal with one more pipetful of water.

6.  Open the petri dish and place a drop of phenolphthalein on the reaction products. Record the color change in the data table.

7.  Using the steel wool, clean the Mg ribbon. Then record the appearance of the now clean Mg ribbon.

8.  With the forceps, move the magnesium from the cover to the water within the petri dish. There is no need to cover the petri dish. Watch for reactions and record the observations in Data Table 1.

9.  Then place a drop of phenolphthalein on the piece of metal. Over the next three minutes, record any color changes or any others signs of reactions that occur.

10.  After that, repeat steps 8 and 9, but this time using the aluminum and record the observations in Data Table 1.

11.  With the forceps, remove and dry off the solid pieces of magnesium and aluminum for use in Part B.

12.  Using the wash bottle, rinse the products of the calcium reaction into the container that the instructor has provided for calcium waste. The other solutions from the petri dishes can be dumped down the drain. Thoroughly wash the petri dishes with water and dry them.

13.  Move on to Part B, if not moving on then clean the laboratory area and wash hands.

Part B

14.  Put on the safety goggles and lab apron and place three micropipets of distilled water into the petri dishes labeled Mg and Al.

15.  Light the lab burner but be careful that everyone is done with Part A because those gases produced are explosive. Then hold the piece of magnesium ribbon over the flames using the crucible tongs. When it lights, hold it over the wire gauze scale making sure not to look directly at the piece of burning magnesium. When the fire burns out, examine the products of the burn and record the observations in the data table.

16.  Then, place the product of the burn into the water in the petri dish that is labeled Mg and then add a drop of phenolphthalein solution. Make sure to record all observations.

17.  Then repeat steps 15-16 using aluminum foil this time. If attempting to light the aluminum are unsuccessful, the3n drop a microspatula of aluminum oxide into the water of the petri dish. After that, place a drop of phenolphthalein on the aluminum oxide and record the observations.

18.  Finally, wash the contents of the two petri dishes down the drain with excess water and dry the dishes. Then just clean up the work area and was hands before leaving.

Observations:

DATA TABLE 1 Observations of Alkaline Earth Metals

Step / Observations (Appearance)
Unreacted Ca / Light grey, gravel like dust
Unreacted Mg / Light silver tint
Ca + water / Sizzled; dispersed in water; water turned cloudy
Ca + water (reaction projucts) / Cloudy
Ca + water + phenolphthalein / Instantly turns fuschia
Mg after cleaning with steel wool / Nothing
Mg + water / Nothing
Unreacted Al / Shiny, chrome like
Mg + water + phenolphthalein / No major color change, slightly pink around metal
Al + water / Nothing
Al + water + phenolphthalein / Nothing

DATA TABLE 2 Comparisons of Alkaline Earth Metals

Reactions / Observations
Mg burning / Turns blindingly bright, then turns white and ashy
Burned Mg + phenolphthalein / Instantly turns fuscia
Al burning / Doesn’t burn
Burned Al + phenolphthalein / Instantly turns light pink ( bubble gum color)

Data: there was no data.

Calculations: There were no calculations.

Conclusions: The experiment was a success. A discovery was made that calcium must be the most reactive out of the three metal samples. Also, it was observed that many reactions were not present when dealing with aluminum.

Error Sources: There were no error sources.

Questions: