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ExposeExciteIgniteMay2012

What you will need • A

What you will need • A butane gas refill cartridge sold at tobacconists or LPG (butane/ propane) gas cartridge (Figure 5.10). You may use methane, propane or butane gas. Their BTUs are in a similar range 3 . Natural gas (methane gas) is found in many laboratories. It is less dense than air so may produce an interesting ‘towering effect’ • Brass tubing, same diameter as gas cartridge metal tube, 3 cm (1.2”) length (Figure 5.11) • Plastic tubing to fit over brass tubing, about 1 m (3.3’) • Latex glove • Bubble solution • Water in open container Here’s how 1. I prefer to use a mobile gas supply such as a butane gas refill cartridge. The gas is only released by the cartridge when pressure is applied. Insert the brass tube into the plastic tube (Figure 5.11). This will trigger the pressure release valve when you exert pressure on the valve and the gas will enter the tubing. Figure 5.10 Figure 5.11 2. Place bubble solution in an clean open container so the gas tube can easily enter it. It should be on a smooth, clean work surface. 3. Open the gas flow by squeezing the brass tubing onto the gas cartridge outlet tube. Bubbles will start frothing and building in the container and overflow the container (Figure 5.13). 3 The British thermal unit (BTU) is a traditional unit of energy equal to about 1.055 kJ 61

Figure 5.12 4. Once you have collected enough bubbles, close the gas supply and remove the tube and cartridge. 5. Fit the glove on one hand and then dip both hands in water. Splash any exposed parts of your arms with water too. 6. Scoop a small quantity of bubbles onto your gloved hand and move to a safe position away from paper and other flammable stuff. Extend your hand away from your body. 7. Light a fire lighter with your free hand and bring the flame slowly closer to the bubbles . . . WHOOSH! The flames should extinguish automatically once all gas is consumed. Figure 5.13 Key Terms Specific heat capacity, latent heat, heat of evaporation, exothermic reactions, combustion, hydrogen bonding References 1. Chang, R., Physical Chemistry for the Chemical & Biological Sciences, University Science Books: Sausalito, 2000 2. Shakhashiri, B. Z.; Chemical Demonstrations: A handbook for teachers of chemistry, Vol. 1, The University of Wisconsin Press: Madison, 1983; p 13 3. Koehler, K. R. (1996), Infrared Spectroscopy. http://www.rwc.uc.edu/koehler/ biophys/6e.html; Dec 2010 4. Gaydon, A. G., Wolfhard, H. G., Flames: Their Structure, Radiation and Temperature, 3 rd ed., Chapman and Hall, London (1970). 62