Candle demonstration

In the nineteenth century, Humphry Davy (1778-1829) speculated that the luminosity of flames is caused by fhe production and ignition of solid particles of carbon as a resulf of the decomposition of a part of the gas. Jons Jakob Berzelius (1779-1848) is said to be the first to describe an ordinary candle flame as consisting of four disfincf zones. Davy s protege, Michael Faraday [9] (1791-1867) gave his Christmas lectures and accom-pan3ung demonstrations to a juvenile audience on "The Chemical History of a Candle" in 1848 and 1860. Around the turn of the century, modem combustion science was established based on the increased understanding of chemistry, physics, and thermodynamics. 

Barrier filters have been tested and shown to have potential in gasification demonstration systems. Ceramic and metal candle-type filters were both tested at a commercial demonstration facility at Varnamo, Sweden, that is an integrated... 

Another everyday example of incandescence is the heating of a metal wire to about 1000 °C in a conventional light bulb. The light emitted from a candle or other form of fire is a further demonstration of incandescence. 

Finding (Blue Grass) AEA-4. The efficacy of using candle filters such as those that AEA has proposed has not been demonstrated. 

Thomas Midgley was also a showman, and when the new product was announced to the world he made a demonstration of his perfect refrigerant at a meeting of the American Chemical Society. He sat on a podium, with a flask of CFC and a lit candle in front of him. He swallowed a mouthful of CFC to show that it was nontoxic and then he blew out the candle to show that it was nonflammable, to thunderous applause. This product created prosperity for many chemists and chemical engineers, who found employment and satisfying careers, handsome profits for investors, and satisfaction for householders, who could enjoy their convenient and safe home refrigerators. 

There is not a law, Faraday told his listeners, under which any part of this universe is governed which does not come into play and is touched upon in these phenomena. There is no better, there is no more open door by which you can enter into the study of natural philosophy than by considering the phenomena of a candle. He then set. out to prove his point by lighting a candle and demonstrating all the processes involved. 

Demonstrate that carbon and carbon-containing compounds form carbon dioxide on combustion. Burn a variety of materials and test for carbon dioxide with limewater. Suitable materials are a candle, wood shavings, charcoal, paraffin etc. 

After 100 seconds, the average migration is only 53 mm. So the beaker will remain filled with CO2 for an extended period. A common lecture demonstration involves pouring the gas from such a beaker over a candle flame, which extinguishes the candle. The carbon dioxide gas can be poured through air because it is heavier than air, yet the low rate of diffusion guarantees that the CO2 molecules will mainly remain together. 

Providing flame retardancy for fibre blends has proved to be a difficult task. Fibre blends, especially blends of natural fibres with synthetic fibres, usually exhibit a flammability that is worse than that of either component alone. Natural fibres develop a great deal of char during pyrolysis, whereas synthetic fibres often melt and drip when heated. This combination of thermal properties in a fabric made from a fibre blend results in a situation where the melted synthetic material is held in the contact with the heat source by the charred natural fibre. The natural fibre char acts as a candle wick for the molten synthetic material, allowing it to bum readily. This can be demonstrated by the LOl values of cotton (18-19), polyester (20-21) and a 50/50 blend of both (LOl 18), indicating ahigher flammability of the blend as described later (Section 8.11). But a rare case of the opposite behaviour is also known (modacrylic fibres with LOl 33 and cotton in blends from 40-60 % can raise the LOl to 35). 

That water is a product of combustion can be demonstrated with an ice cube and a nonplastic glass or a nonplastic saucer. Invert the glass over the candle flame for a minute with the ice cube balanced on top of the glass, on the outside. Moisture from the flame will condense on the inside of the glass. Alternatively, place the ice cube on the saucer and then hold the saucer over the flame without touching the flame. Moisture will condense on the bottom. 

The biomass fuelled IGCC demonstration plant at Vamamo consists of a 18 MW pressurised circulating fluidised bed gasifier, a 4,2 MW gas turbine and a 1,8 MW steam turbine. The low heat value gas produced in the gasifier is cooled in a gas cooler and cleaned in a candle filter at a temperature of 350-400°C before it is combusted in the gas turbine. The flue gas from the gas turbine is used for the production of steam in the heat recovery steam generator. The steam is superheated, together with steam from the gas cooler, and supplied to the steam turbine. Besides electricity, 9 MW heat for district heating purposes is produced. 

Problem Because of everyday experiences, children tend to believe in the loss of mass or of the material becoming lighter when alcohol, paper or candles are burned. Even after observing that iron wool glows, students state that the formed black substance is lighter than the iron before . Using a balance, one demonstrates that the black substance solid iron oxide is heavier due to the reaction with oxygen. These experiments show the increase in mass accompanied by the formation of a solid substance, like metal oxides or phosphorus oxide in an open system. 

Procedure and Observation Bend a wire into any shape and hold it in the flame of a match or candle the wire spontaneously regains its shape (demonstrate it by using an overhead projector). Dip the wire which is re-formed into hot water and observe. Either press together or stretch out springs and place into hot water (overhead projector) once again the original form returns. 

---