Aluminium Foil and NaOH

 

DESCRIPTION:
This demo simulates what happens when Drano is poured down a clogged drain; the hydrogen gas produced forces gunk out of the drain.
2Al + 2NaOH + 6H2O → 2NaAl(OH)4 + 3H2
Also, this demonstration is a good safety example of why bases need to be handled carefully – they can be corrosive, especially to metals. If the hydrogen gas is collected and ignited, this demo shows the safety hazards that evolved gases can have.

TOPICS COVERED:
complex ion reactions
redox
exothermic reactions
evolution of a gas
chemical change
safety

MATERIALS NEEDED:
– aluminum foil
– NaOH pellets
– Erlenmeyer flask
– water dropper

PROCEDURE:
1. Place a small amount of aluminum foil in the flask
2. Put a few pellets of NaOH on the aluminum foil
3. Squirt some water onto the NaOH pellets

ADDITIONAL COMMENTS:
If the reaction starts to slow down (bubbling appears to stop), squirt a little more water on the reaction to ensure any reactants left will mix together. You can place a balloon on top of the flask to collect hydrogen gas to ignite. See Hydrogen Balloons

SAFETY:
NaOH pellets can cause severe burns so caution should be taken. The flask should be rinsed thoroughly with water to insure that there is nothing left to react before putting the remaining aluminum foil in the trash, everything else can go down the drain.

REFERENCES:
Shakhashiri, B.Z. Chemical Demonstrations;  University of Wisconsin Press: Madison, 1989; Vol. 3, pp 128 – 131.

Handout

This problem set practices balancing a chemical equation, finding the limiting reactant and theoretical yield, and using Avogadro’s number.

This lesson plan‘s topic is the Evidences of Chemical Reactions. Students learn the various evidences, then they get a change to practice identifying them with a hands on activity. Aluminum Foil and NaOH is used in the activity portion of this lesson.