Kristen Gerstberger

The Flaming Wood Splint

Science Concept-Polarity, Solubility The properties of oxygen and carbon dioxide are different when exposed to a flame.

Materials-

• 2- 125 mL Erlenmeyer flasks
• 120 mL water
• 2 Alka Seltzer Tablets
• 2 Efferdent Tablets
• Wood Splint
• Lighter
• 2 small watch glasses as covers

Directions-

• Pour 60 mL of water in each flask.
• Place one tablet of Alka Seltzer in one flask, and one tablet of Efferdent in the second flask.
• After a few seconds, add the second Efferdent in the second flask, and place one of the watch glasses over the top of the flask to collect pure oxygen inside the flask.
• Place a second Alka Seltzer in the first flask.
• Light the wood splint and place the flame into the first flask-with the Alka Seltzer-without touching the liquid at the bottom of the flask. The flame should go out.
• Light the wood splint again, and blow out the flame. Make sure the splint has a glowing ember on the end.
• Put the splint with the glowing ember into the second flask with the Efferdent. The splint should burst into a flame.
• Extinguish the flame again by placing it into the first flask.

AlkaSeltzer Graphic in a new window

Efferdent Graphic in a new window

Introduction- How many of you have taken Alka Seltzer tablets when you are sick. For those of you who haven't, Alka Seltzer is a pain relief medicine, which is in the form of a solid tablet. When dropped into water, the tablet begins to dissolve and it fizzes at the bottom of the glass. Efferdent is a denture cleaner, which is also in the tablet form and will dissolve and fizz at the bottom of a glass of water. While these tablets appear to look quite similar, they have very different effects on a flame.

Explanation- In the first flask, Alka Seltzer tablets were dissolved, which produced carbon dioxide gas due to the sodium bicarbonate and citric acid in the tablet. Carbon dioxide puts out a flame, so when the wooden splint was placed into the flask, the flame was extinguished. The second beaker had Efferdent tablets dissolved in it, and produced pure and concentrated oxygen gas. The Efferdent tablet has a solid form of peroxide in it, plus a built in catalyst, which speeds up a chemical reaction. When dropped into water, the Efferdent decomposes, and with the help of the built in catalyst, a pure oxygen gas rises from the bottom of the flask. By trapping the gas inside the flask with the watch glass, the oxygen gas inside becomes very concentrated. When the splint with a glowing ember is placed inside, the flame will ignite again, because oxygen supports combustion very well.

Additional: Why do the gases bubble out of the solution? Oxygen and carbon dioxide are both non-polar gases. The non-polar gases are not soluble in the polar water solution, hence the gases bubble out of the liquid water.

Alka Seltzer:

Na₂CO₃ + Citric Acid + Water --->> CO₂ + H₂O + Sodium Citrate

Efferdent:

H₂O₂ (Peroxide) + Water + Catalyst = O₂ + H₂O

Reference - Ophardt, C. E. original idea - January, 2002