Safe Swimming with Sodium
Science Concept: This experiment demonstrates the way that sodium metal reacts with water, and also how universal indicator reacts with sodium hydroxide.
* sodium metal (pea size) Graphic of Sodium
* 1,000ml graduated cylinder
* universal indicator
* eye dropper
* safety goggles
* paper towels
1. Fill the graduated cylinder with 800ml of water.
2. Add about one eye dropper full of universal indicator (the water will begin to turn green).
3. Remove a pea sized chunk of sodium metal with the tweezers from the mineral oil that the sodium metal is kept in. (DON'T TOUCH THE SODIUM METAL WITH YOUR HANDS).
4. Place the sodium metal on a paper towel and blot the mineral oil off the sodium metal (to make sure that the mineral oil doesn't interfere with the experiment).
5. With the tweezers, carefully place the sodium metal in the graduated cylinder. Step back and watch the reaction!!!
Introduction: I brought a very special metal with me today...This metal isn't like most metals, it can do a very cool trick. Watch very closely to see what my magical metal can do!
Explanation: The sodium metal is very reactive when it is exposed to water or moisture. When the sodium metal is reacting with the water, the sodium metal goes to the ion state and becomes a stable element. The reaction produces sodium ions and hydrogen gas, which is called sodium hydroxide. The hydrogen gas is what causes the sodium to "swim around" because the gas is pushing the sodium. The sodium metal is less dense than the water which allows the sodium metal to "dance and swim around" instead of sinking to the bottom of the cylinder. The universal indicator reacts with the sodium hydroxide, which is a base that makes the indicator turn from green to purple.
2Na + 2H20 -----> 2NaOH + H2 + heat
sodium metal + water -------> sodium hydroxide + hydrogen gas + heat
Safety: Wear safety goggles!!! Do not touch sodium metal to skin!!!
Waste Disposal: May pour all materials down the drain. Any excess sodium metal must be put back in mineral oil.
Source: Public Domain