The reactivity of the group 2 metals

Students will be able to discover that group 1 metals are more reactive than group 2

This experiment should take 30 minutes.

Equipment

Apparatus

• Safety glasses
• 100 cm³ beakers x 2
• Measuring cylinder (50 cm³)

Part two

• Test tube rack
• Test tube
• Splint 

Chemicals

• Hydrochloric acid 0.4 mol dm^–3
• Magnesium ribbon (5 mm piece)
• Fresh calcium (5 mm piece)

Health, safety and technical notes

• Read our standard health and safety guidance.
• Always wear eye protection
• Hydrochloric acid at this concentration is currently not classified as hazardous, see CLEAPSS Hazcard HC047a.
• Magnesium ribbon may carry the same hazard warnings as magnesium powder: DANGER flammable solid; self-heating in large quantities - may catch fire; in contact with water releases flammable gases, see CLEAPSS Hazcard HC059a.
• Calcium: DANGER in contact with water releases flammable gases, see CLEAPSS Hazcard HC016.
• These reactions produce hydrogen gas and are exothermic – ensure only small pieces of each metal are used with sufficient quantities of the solution, as in the instructions.

Procedure

1. Use the measuring cylinder to measure and carefully pour 40 cm³ of hydrochloric acid solution into each beaker.
2. Into one beaker drop a small piece of magnesium ribbon (5 mm).
3. Into the other, drop a small piece of calcium (5 mm).
4. Compare the reactivity of the two metals.

Part two

1. Carefully pour hydrochloric acid solution into the test tube to roughly one quarter full.
2. Drop a piece of magnesium into the test-tube and put your thumb over the end.
3. When the pressure can be felt, take your thumb off and test the gas with a lighted splint.
4. Record what happens.

Notes

Discussion about how to judge the speed of the reaction is advisable.

Remind students about the test for hydrogen.

Calcium can be distributed on pieces of filter paper.

Group 1 is the most reactive group of metals. The Group 1 metals get more reactive the lower they are in the group. Group 2 metals are also reactive.

Questions

1. Which is the more reactive, magnesium or calcium?
2. Write word equations for these reactions.
3. Write formula equations for these reactions

Answers

1. Calcium.
2. Magnesium + hydrochloric acid → magnesium chloride + hydrogen
   1. Calcium + hydrochloric acid → calcium chloride + hydrogen
3. Mg + 2HCl → MgCl₂ + H_2; Ca + 2HCl → CaCl₂ + H₂