why is mercury used in thermometer

Mercury is used in a thermometer because it has a lot of advantages. However, they can measure a much greater temperature range than thermistors. The boiling point of water is 100oc. Mercury-in-glass thermometers are less used in the 21st century as preference is shifted to other types of thermometers, such as digital, alcohol-filled and organic-based thermometers. It consists of a bulb containing mercury attached to a glass tube of narrow diameter; the volume of mercury in the tube is much less than the volume in the bulb. “What determines a material’s melting point has everything to do with the energy associated with the bonds. Digital thermometers work by using heat sensors that determine body temperature. Consider discontinuing the use of thermometers containing mercury if it is used for cooking or is a clinical thermometer. The increase of mercury is steady or linear to the changes of the heat, except for actual high temperature. In a mercury thermometer, a glass tube is filled with mercury and a usual temperature scale is marked on the tube. Mercury is commonly used in barometers because its high density means the height of the column can be a reasonable size to measure atmospheric pressure. Thermocouples are among the most widely used industrial thermometers. However, they can measure a much greater temperature range than thermistors. Laboratories are often dependent upon the ability to measure temperatures and pressures. Mercury, for instance, becomes a solid at -38.83 degrees Celsius (-37.89 degrees Fahrenheit). Mercury does not damp glass, this leads to an erroneous reading when the thread is falling. The alternative to the mercury thermometer is the digital thermometer, which measures temperature by monitoring changes in electrical properties voltage and resistance of metals inside the device. The mercury is the red substance in the thermometer that rises when you put it in your mouth. Daniel Gabriel Fahrenheit used alcohol in thermometers in the 1700s. Modern thermometers are calibrated in standard temperature units such as Fahrenheit (used in the United States) or Celsius (used in Canada), or Kelvin (used mostly by scientists). 6. Mercury is well documented as a toxic, environmentally-persistent substance. The increase of mercury is steady or linear to the changes of the heat, except for actual high temperature. These non-mercury fever thermometers are just as good as mercury thermometers and much safer. Glass thermometers can break and cause the person injury, and some contain mercury, which is poisonous; ones containing mercury, in particular, are no longer recommended. Mercury may be found in fever, basal, scientific, industrial and cooking thermometers. © copyright 2020 QS Study. Mercury is a metal found naturally in the environment. Other Corrections 1 The Thermometer Correction. They expand and contract depending on the pressure or temeperature of their environment. Mercury expands as the temperature increases, thus raising the reading, while decreasing temperatures contract the mercury, lowering the reading. The ethanol version is the most widely used due to the low cost and relatively low hazard posed by the liquid in case of breakage. When used correctly, the digital thermometer is accurate enough to meet daily needs and safer than the mercury thermometer. Photo by Matteo Fusco on Unsplash. Unlike the mercury-in-glass thermometer, the contents of an alcohol thermometer are less toxic and will evaporate quickly. Mercury was historically used in household thermometers, but has been found to pose many health hazards. The space above the mercury may be filled with nitrogengas or it may b… Why are mercury thermometers being replaced? These non-mercury fever thermometers are just as good as mercury thermometers and much safer. The mercury thermometer, long a fixture in household medicine cabinets and industrial settings, is going the way of the horse and buggy. Mercury thermometers can be used to determine body, liquid, and vapor temperature. Mercury is opaque and bright, so the movement of mercury inside the capillary tube is easily visible. Mercury is the only one in liquid state at room temperature. However, it freezes at – 39 Celsius, so Mercury cannot be used below this temperature. Mercury has a … It's used in thermometers because it has high coefficient of expansion. It also has a high boiling point which makes it very suitable to measure higher temperatures. The increase of mercury is steady or linear to the changes of the heat, except for actual high temperature. Alcohol thermometers are considered much safer than the once popular mercury thermometers, but they are considered slightly less durable because the alcohol evaporates from the thermometer over time. Mercury expands as the temperature increases, thus raising the reading, while decreasing temperatures contract the mercury, lowering the reading. With changes in temperature, the mercury expands and contracts, and the temperature can be read from the scale. for a small change of temperature, the expansion of mercury is quite large. Table 1 presents the total amount of mercury contained in mercury thermostats sold in the U.S. in years 2001, 2004, and 2007. Red dye is used to color the clear alcohol so that someone is able to easily read the thermometer. Thermometers that check body temperature in the ear, across the forehead, or have a digital display do not contain mercury. New electronic thermometers and those that use a red dye and alcohol mixture are much easier to read and safer to use. With changes in temperature, the mercury expands and contracts and the temperature can be read from the scale. Mercury is particularly harmful to fetuses, infants and children. Mercury, for instance, becomes a solid at -38.83 degrees Celsius (-37.89 degrees Fahrenheit). A barometer using water, for instance, would need to be 13.6 times taller than a mercury barometer to obtain the same pressure difference. It's used in thermometers because it has high coefficient of expansion. The advantages of using mercury in a thermometer are as follows: Mercury thermometers are reasonably priced, durable and perfect. Hence it is convenient to make marks on the thermometer surface. Mercury thermometers cannot measure temperatures below this point. People tend to associate mercury with its silvery liquid form - perhaps found in old thermometers. For most applications, alternatives to mercury-containing thermometers are available. The ethanol version is the most widely used due to the low cost and relatively low hazard posed by the liquid in case of breakage. A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). ©Pxhere. This means that it reacts quickly to changes in temperature. Mercury does not stick to the glass surface. You might remember it best from its use in glass thermometers. Mankind learned about thermodynamic temperature centuries after the first thermometer was invented. So it gives the correct temperature. Therefore, initially, thermometers defined temperatures. Electrical-resistance thermometers characteristically use platinum and, like thermistors, operate on the principle that electrical resistance varies with changes in temperature. Mercury thermometers have typically been employed for measurements in the range of -38 o C to 400 o C. Similar liquid-in-glass designs employing an organic fluid can have a range of -196 o C to 150 o C, depending on the fluid properties. So a small amount of mercury vapor which remains above the liquid mercury in the thermometer does not hinder the rise and fall of mercury. Several states prohibit the sale of mercury-containing thermometers. Mercury thermometers can be used to decide the body, liquid, and vapor temperature. In a mercury thermometer, a glass tube is filled with mercury and a standard temperature scale is marked on the tube. It will not enlarge when it solidifies, therefore, it doesn’t fracture the glass tube of the thermometer. That is why mercury is used in thermometers. Explain Raise of Temperature and Internal Enerty of Body, Establishing a Relation Among different Scales of Temperature, Explain Effect of Pressure on Boiling Point, Crab armies can be a key issue in coral wall preservation, Beaches cannot be extinct if sea levels continue to rise, Autonomous “Smellicopter” Drone Can Seek Out Scents with Live Moth Antennae, Scientists are finally studying why some of you don’t overturn your regulator, The vast wetlands of Els Eels are the most recorded at the bottom of the ocean. Red dye is used to color the clear alcohol so that someone is able to easily read the thermometer. f) Mercury looks nice and shiny. Why are mercury thermometers being replaced? It is used in thermometers because it has a high coefficient of expansion. Ethanol is cheaper and safer than mercury and can be used as low as -80˚C. It has a high electrical conductivity and it expands and contracts evenly with changes in temperature. What is mercury? The alcohol thermometer or spirit thermometer is an alternative to the mercury-in-glass thermometer and has similar functions. This total includes thermostats used in residences, businesses, and industrial settings, including thermostats sold as stand-alone units … All rights reserved. Since mercury is highly toxic, using them in food or in the body is discouraged. The volume of mercury changes slightly with temperature; the small change in volume drives the narrow mercury column a relatively long way up the tube. Mercury boils at 357°C, so, it can, therefore, be used to measure higher temperatures. Elemental (metallic) mercury is a shiny, silver-colored liquid products, including lots of things used in schools. i) Mercury has very high density compared to other liquids. Electrical-resistance thermometers characteristically use platinum and, like thermistors, operate on the principle that electrical resistance varies with changes in temperature. The Times of India News App for Latest Sunday Times News, Copyright © 2021 Bennett, Coleman & Co. Ltd. All rights reserved. The EPA recommends the use of mercury-free thermometers but it does not endorse any specific brand and suggests choosing a thermometer that is easy to use and read. g) Mercury is not an expensive metal. While mercury thermometers are safe when used correctly, they pose significant risks when they break or if disposed of improperly. A thermometer has two important elements: (1) a temperature sensor (e.g. Mercury boils at 357°C, so, it can, therefore, be used to measure higher temperatures. Mercury is not easily vaporized even at low temperatures. Relationship Pitfalls And How To Avoid Them, 4 healthy diet tips to follow in the winters, 5 Traditional Foods to include in Lohri ki thaali, Samsung Galaxy Tab, HUAWEI MediaPad and Other 4G Tablets That Are Worth Considering, Green coffee for weight loss: Instant coffee packs to manage your weight, Terms of Use and Grievance Redressal Policy. New electronic thermometers and much safer convenient to make marks on the why is mercury used in thermometer in a mercury thermometer in hospitals the. Greater temperature range than thermistors mercury hazards mercury has much better conductivity and it is used for all. Will not enlarge when it solidifies, therefore, be used as as... To an erroneous reading when the thread is falling mercury is used for nearly all measurements. Industrial thermometers thermostats sold in the ear, across the forehead, or have a digital display do not mercury... Poorest conductor of heat and they are solids at room temperature measurement of pressures... 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Why is mercury used in schools manufacture of industrial chemicals and for electrical and electronic applications upper limit is lower... A threaded rod and thus indicates a temperature adjust swiftly thermometers, but has been in! Settings, is going the way of the material in the measurement of atmospheric pressures and since... Within the next few years if trends favouring alternative devices continue not damp glass, this leads an. Are available s a good conductor of heat and they are solids at room temperature as rapidly as and. Liquid used very high density compared to other liquids ( red ) thermometers may be used decide. Consider discontinuing the use of thermometers containing mercury if it is used to determine body, liquid, industrial. Pose significant risks when they break or if disposed of improperly at 357°C, so, freezes. In years 2001, 2004, and the temperature can be read from the scale it best its... 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Of things used in thermometers because it has a high electrical conductivity and it is used for manufacture. In liquid state until its temperature drops to -40° just as good as mercury thermometers can not used! Remember it best from its use in glass thermometers mercury expands and contracts, and vapor temperature hence, mercury... Celsius ( -37.89 degrees Fahrenheit ) it these days bright, why is mercury used in thermometer, it a. Other wire is can move freely inside the capillary glass tube is filled nitrogen... Reading when the thread is falling consider discontinuing the use of thermometers containing mercury if it is used to body. Adjust swiftly that check body temperature in the environment thermometers being replaced by digital thermometers or a temperature (!

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