Active Metals Lab Practical
I) Purpose: you are going to react Na, K, Al, Mg and Ca with 100-200ml de-ionized
water and observe the intensity(violence) and duration(time) of the reaction. Using this
information and the three factors that affect ionization energy you will explain the trends
in the 5 element block.
II) Theory: Central to this lab is the interplay between 1) Shielding, 2) Nuclear Charge
and 3) Full and ½ Full level stability. Nuclear charge increases left to right. Shielding is
less for Na, Mg and Al, more for K and Ca. Mg and Ca both have full S sublevel
stability. All reactions follow these patterns:
2Na(s) + 2H2O(l)  2NaOH(aq) + H2(g)
or
Ca(s) + 2H2O(l)  Ca(OH)2(aq) + H2(g)
or
2Al(s) + 6H2O  2Al(OH)3 + 3H2(g)
Completed reaction should have a very High pH(10+) due to the extreme basicity of all
hydroxides. Use pH paper provided by Welch to determine this after all reactions are
complete. All complete reactions can go down the sink after. Incomplete or no reaction
need to have solid residue in the wastebasket. Have fun!