To compare the reactivity of various metals by observing their reaction with hydrochloric acid.
Materials:
2 M hydrochloric acid
Detergent
Test tubes and test tube rack
0.5 pieces of magnesium, aluminium, iron, zinc and cooper
Sand paper
Ruler
Timer
Bench mat
Method:
1. The surface of the magnesium was cleaned with a piece of sandpaper
2. The Magnesium was placed into a test tube
3. Three Drops of detergent were added to the test tube
4. 2cm of hydrochloric acid was added to the test tube
5. The timer was set to 5 minutes
6. Observations were recorded, including the height of foam, in a table
7. The process was repeated for the remaining metals
Hypothesis:
It was predicted that Magnesium would be most reactive metal in the experiment.
Background:
As the group number decreases, reactivity increases. As the period increases, the most reactive is towards the bottom. The alkali metals (Group 1 metals) are identified as the most reactive of all present elements on the periodic table. Seeing as potassium and sodium are both found in group 1, this will suggest that potassium will be the most reactive metal. Additionally, potassium should be more reactive than sodium as its single valence electron is placed more distant from the nucleus than sodium, meaning less energy is needed to remove the valence electron, therefore meaning the reactivity is higher.
Independent variable:
The metals were the factor that was purposely change throughout the practical.
Dependent variable:
The height of the foam was the factor being measured throughout the practical.
Controlled variable:
Detergent and hydrochloric acid were the factors being controlled throughout the practical.
Results:
Group results
Metal Observation Height of foam (cm)
Magnesium
Aluminium
Iron
Zinc
Copper Cloudy, frothy
Cloudy, least reactive
Bubbly cloudy
Cloudy, bubbly, most reactive, turned white when stirred
Cloudy, bubbly 0.5
0
1
2.5
1.5
Na bubbled very