A Bunsen burner is a laboratory device used to heat substances for experiments. It consists of a metal tube with a base that connects to a fuel source and a valve to control gas flow. The burner produces a yellow, smoky flame when the air holes are closed and a blue flame when they are open. It is used to heat material in test tubes and can also be used for flame testing. Safety precautions must be taken when using the burner. It was invented by Robert Wilhelm Bunsen in the mid-1800s and allowed for the discovery of new elements.
A Bunsen burner is a laboratory device used to heat substances for various experiments. In essence, these are small gas burners with an adjustable flame, which can be manipulated at the base by controlling the amount of gas and air introduced. They are a common sight in chemistry labs and most scientists are familiar with how they work. To provide moderate heating, particularly of liquids in beakers and flasks, a hot plate may be preferred, but when high temperatures are required or when heating materials in test tubes, a Bunsen burner is required.
Design and operation
The device consists of a vertical metal tube connected to a broad base that is weighted so that it is not easily knocked over. The base includes a nozzle for connection to a fuel source, as well as a valve to control gas flow and a smoke regulator to control the amount of air admitted through one or more small air holes at the base of the tube. The gas mixes with air at the bottom of the tube and then rises to the top of the burner, where it can be lit with a match or lighter.
With the air holes closed, a yellow, smoky flame is produced due to incomplete combustion of the charcoal. Natural gas consists mainly of methane, a carbon-hydrogen compound; if there is insufficient air, not all of the carbon burns and instead forms tiny soot particles that glow yellow in the heat. This flame is not used for heating, as it will deposit soot on anything in or on it, and is not hot enough for most purposes in any case.
When the vents are open, air is drawn into the burner, allowing the natural gas fuel to burn completely, and a blue flame is produced. This flame is much hotter – reaching up to 2732°F (1500°C) – and is one used for heating purposes. It normally has a dim outer cone and a more intensely blue inner cone, the tip of which is the hottest part of the flame. The device can be adapted to run on bottled propane or butane, so it can be used in locations without a gas supply.
it is used
The primary use of the Bunsen burner is as a means of heating substances strongly during chemistry experiments. It is often used to heat material in a glass test tube. If very strong heating is required, strong enough to melt glass, a small porcelain dish known as a crucible can be used.
Bunsen burners can also be employed in a crude form of chemical analysis known as flame testing. Many elements, particularly metals, emit light of particular colors when heated in a flame. These items can often be detected by placing them in a Bunsen flame; for example, sodium gives a yellow flame, potassium gives lilac and barium green. This method has its limitations and drawbacks – for example, the strong yellow color of sodium can mask the presence of other metals – and has largely been surpassed by spectroscopes, but it can be a useful rapid test in some cases.
Safety
Many laboratory accidents involve burns related to open flames, and as a result new students are carefully trained in the use of gas burners. The student must always wear safety goggles and make sure that his/her hair and clothes are secured so that they do not come into contact with the flame. Flammable substances should be kept away from the heat source and someone should always be present to supervise it. When lit, but not in use, the air hole should be closed so that the flame is clearly visible – the warm blue flame can be difficult to see in bright light.
When heating small objects in the flame, a pair of tongs should be used. Larger items, such as bottles and glasses, should be placed on a stand or held in a clamp. The flexible rubber tubing connecting the Bunsen burner to the gas nozzle on the lab bench must be secure, with no traces of leaks. Be careful touching things that have been exposed to the heat of the burner, especially glass objects, which can stay hot for some time.
History
Like many scientific inventions, the burner reflects the name of the scientist overseeing the laboratory where it was invented, rather than the actual inventor. Robert Wilhelm Bunsen was a well-known chemist in Germany in the mid-1800s who took a particular interest in examining the spectra of different elements—the unique set of wavelengths, or colors, of light each emits when heated. To do this effectively, he needed something that produced a very hot flame with a low brightness, so that his light would not obscure the wraiths.
He came up with the idea of mixing natural gas with air before combustion and commissioned a laboratory technician, Peter Desaga, to design and build the burner. The resulting device allowed for significant control over flame height and intensity and was very successful. He quickly became associated with the Bunsen laboratory and popularly known as a Bunsen burner.
Not long after its invention, the device enabled Bunsen to discover two new elements, cesium and rubidium, from their previously unpublished spectra. Indeed, the elements take their name from the spectral lines they produce: sky blue and dark red, respectively. Other chemists went on to discover many more new elements in this way.
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