Mercury is the only one in liquid state at room temperature. The key thing with thermometers is that they must be accurate and also be able to detect a change in temperature to the smallest degree, and that’s why mercury was first used. Mercury is the only one which is liquid at room temperature, which makes it easy to work with. It will not enlarge when it solidifies, therefore, it doesn’t fracture the glass tube of the thermometer. Mercury is used in thermometers. Infrared (ear) thermometers may be used as an alternative to mercury fever thermometers. Most metals are good conductors of heat and they are solids at room temperature. Mercury boils at 357°C, so, it can, therefore, be used to measure higher temperatures. Liquid thermometers can be limited by the type of liquid used. These non-mercury fever thermometers are just as good as mercury thermometers and much safer. Thermocouples are among the most widely used industrial thermometers. Mankind learned about thermodynamic temperature centuries after the first thermometer was invented. In addition to the answer and the comment given, the use of mercury in thermometers had another advantage frequently used in the lab: Mercury, as a metal, has a high electrical conductivity. “What determines a material’s melting point has everything to do with the energy associated with the bonds. 6. Metallic mercury is toxic, and also expensive. Mercury thermometers can be used to decide the body, liquid, and vapor temperature. More importantly, the temperature measurement is only a reference, whether to administer medicine to children or take them to the hospital depends on the judgment of … j) Mercury has a low latent heat for evaporation Since mercury is highly toxic, using them in food or in the body is discouraged. A thermometer has two important elements: (1) a temperature sensor (e.g. Mercury may be found in fever, basal, scientific, industrial and cooking thermometers. Red dye is used to color the clear alcohol so that someone is able to easily read the thermometer. Most metals are good conductors of heat and they are solids at room temperature. Several states prohibit the sale of mercury-containing thermometers. Why are mercury thermometers being replaced? The boiling point of water is 100oc. Mercury, for instance, becomes a solid at -38.83 degrees Celsius (-37.89 degrees Fahrenheit). i) Mercury has very high density compared to other liquids. A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). These thermometers are used in households, laboratory experiments, and industrial applications. You might remember it best from its use in glass thermometers. Wilfrid Francis, Martin C. Peters, in Fuels and Fuel Technology (Second Edition), 1980. So it can move freely inside the capillary glass tube. 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 thermometers are being phased out in the US. Mercury thermometers are used in: power plants and piping; chemical tanks; heating and cooling equipment; canneries; ships; paint kettles etc. Unlike the mercury-in-glass thermometer, the contents of an alcohol thermometer are less toxic and will evaporate quickly. Broken mercury-filled thermometers … Continued With changes in temperature, the mercury expands and contracts, and the temperature can be read from the scale. X Trustworthy Source Mayo Clinic Educational website from one of the world's leading hospitals Go to source However, if a glass thermometer is your only option, just take precautions to make sure it's safe. Mercury is a metal found naturally in the environment. The alcohol thermometer or spirit thermometer is an alternative to the mercury-in-glass thermometer and has similar functions. Why is mercury used in thermometers despite being the poorest conductor of heat? 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 is an element that is the only metal found in liquid form at room temperature. Mercury has a … Mercury boils at 357°C, so, it can, therefore, be used to measure higher temperatures. Hence, the slightest change in temperature is notable when it's used in a thermometer. For reprint rights: Times Syndication Service. Mercury does not damp glass, this leads to an erroneous reading when the thread is falling. While mercury thermometers are safe when used correctly, they pose significant risks when they break or if disposed of improperly. 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. The first thermometers manufactured contained water but the fact that water freezes at 32 degrees Fahrenheit led manufacturers to switch to mercury. Therefore, initially, thermometers defined temperatures. Historically, mercury thermometers have been used for nearly all temperature measurements because of their accuracy and low cost. © copyright 2020 QS Study. Also, it has a shiny appearance and doesn't stick to the glass surface of glass. Mercury is opaque and bright, so the movement of mercury inside the capillary tube is easily visible. 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. Digital or spirit-filled (red) thermometers are a safer alternative. It can be found in meteorological equipment like thermometers and barometers. However, ethanol boils at 78°C (172.4°F), which means its upper limit is much lower than mercury thermometers. Their use is gradually more being restricted to industrial and technical applications, as safety and environmental issues are demanding stricter laws on the removal of products containing mercury. Mercury expands as the temperature increases, thus raising the reading, while decreasing temperatures contract the mercury, lowering the reading. All rights reserved. The first thermometers, however, weren’t thermos or heat measurers, but thermo-scopes, devices that merely signaled whether the temperature was high or low. Mercury boils at 357°C, so, it can, therefore, be used to measure higher temperatures. 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). The mercury is the red substance in the thermometer that rises when you put it in your mouth. 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. Mercury has been replaced largely by alcohol for use in thermometers. The melting point of water is 0oc but when you see mercury freezing point (melting point) -38.83oc and the boiling point of the mercury is 356.73oc. However, they can measure a much greater temperature range than thermistors. f) Mercury looks nice and shiny g) Mercury is not an expensive metal h) Mercury expands a lot with temperature i) Mercury has very high density compared to other liquids j) Mercury has a low latent heat for evaporation 6. Mercury is less volatile. Mercury's Use: Despite mercury being toxic to humans in its natural form, it has a variety of everyday uses. When two bodies touch, their temperature adjusts, which means that the colder gets warmer, the warmer gets colder. f) Mercury looks nice and shiny. ©Pxhere. It also has a high boiling point which makes it very suitable to measure higher temperatures. In a thermometer, a glass bulb attached to a glass capillary tube is filled with mercury. Electrical-resistance thermometers characteristically use platinum and, like thermistors, operate on the principle that electrical resistance varies with changes in temperature. So it gives the correct temperature. New electronic thermometers and those that use a red dye and alcohol mixture are much easier to read and safer to use. Unlike the mercury-in-glass thermometer, the contents of an alcohol thermometer are less toxic and will evaporate quickly. People tend to associate mercury with its silvery liquid form - perhaps found in old thermometers. Thermometers that check body temperature in the ear, across the forehead, or have a digital display do not contain mercury. However, their use is increasingly being restricted to industrial and scientific applications, as safety and environmental issues are demanding stricter laws on the disposal of products containing mercury. Dangers of Mercury Mercury is a very dense element that is the only metal to exist as a liquid at room temperature. Daniel Gabriel Fahrenheit used alcohol in thermometers in the 1700s. Thermometers containing mercury can be easily identified by the colour of the material in the bulb. This total includes thermostats used in residences, businesses, and industrial settings, including thermostats sold as stand-alone units … In a mercury or alcohol thermometer, the liquid expands as it is heated and contracts when it is cooled, so the length of the liquid column is longer or shorter depending on the temperature. Alcohols, such as ethanol, boil at about 78 degrees Celsius (172 degrees Fahrenheit). Digital thermometers work by using heat sensors that determine body temperature. This means that it reacts quickly to changes in temperature. Mercury thermometers cannot measure temperatures below this point. Mercury thermometers can be used to determine body, liquid, and vapor temperature. Consider discontinuing the use of thermometers containing mercury if it is used for cooking or is a clinical thermometer. Actually, we try to avoid it these days. Unfortunately, this measurement is not without hazard. In a mercury thermometer, a glass tube is filled with mercury and a standard temperature scale is marked on the tube. Why are mercury thermometers being replaced? Mercury Hazards Mercury has been used in the measurement of atmospheric pressures and temperatures since the mid 1600s. The increase of mercury is steady or linear to the changes of the heat, except for actual high temperature. For most applications, alternatives to mercury-containing thermometers are available. Mercury does not stick to the glass surface. 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. Hence it is convenient to make marks on the thermometer surface. The melting point of water is 0 o c but when you see mercury freezing point (melting point) -38.83 o c and the boiling point of the mercury is 356.73 o c. The boiling point of water is 100 o c. So based on this criteria the mercury is having the temperature reading capacity compared to water. What is the primary reason why liquid mercury (Hg) has been commonly used in thermometers for more than a century? If a mercury in glass thermometer is used, the observed firing temperature and the final temperature must be corrected as prescribed by the certificate issued with the instrument.. 2 Correction for the Cotton Thread. Will the replacement of mercury thermometers be problematic? Thermometers that check body temperature in the ear, across the forehead, or have a digital display do not contain mercury. Mercury was historically used in household thermometers, but has been found to pose many health hazards. There are a number of different model types, sizes, and specifications, but the general operating principle is about the same in all cases. In a mercury thermometer, a glass tube is filled with mercury and a usual temperature scale is marked on the tube. Will the replacement of mercury thermometers be problematic? The mercury-in-glass or mercury thermometer was invented by physicist Daniel Gabriel Fahrenheit in Amsterdam (1714). Elemental (metallic) mercury is a shiny, silver-colored liquid products, including lots of things used in schools. However, they present many safety and environmental hazards. Mercury is the only one in a liquid state at room temperature. This continues until they are warm. For most applications, alternatives to mercury-containing thermometers are available. Liquid thermometers can be limited by the type of liquid used. Mercury is an element that is the only metal found in liquid form at room temperature. 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. That is why mercury is used in thermometers. It has a high electrical conductivity and it expands and contracts evenly with changes in temperature. Somewhere in the middle is mercury, which stays in a liquid state until its temperature drops to -40°. A: Mercury has been used in heat and pressure measuring instruments since the first intruments were made.. Metals are very good conducters of heat. 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. Unfortunately, mercury is toxic and it is replaced almost everywhere. 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 increase of mercury is steady or linear to the changes of the heat, except for actual high temperature. It has a high electrical conductivity and it expands and contracts evenly with changes in temperature. The other wire is can move along a threaded rod. h) Mercury expands a lot with temperature. It can be found in meteorological equipment like thermometers and barometers. Its stage indicates the temperature as rapidly as potential and perfectly. Why are we using Mercury in thermometer, reasons are followed:. It's used in thermometers because it has high coefficient of expansion. Thermometer | Why is mercury used in thermometer | precautions using thermometer | PB Learning Hub The mercury thermometer, long a fixture in household medicine cabinets and industrial settings, is going the way of the horse and buggy. These devices weren’t calibrated to a standard scale; they would just make crude or vague assessments.The in… Dangers of Mercury Mercury is a very dense element that is the only metal to exist as a liquid at room temperature. It is a metal, so it’s a good conductor of heat. The space above the mercury may be filled with nitrogengas or it may b… Alcohols, such as ethanol, boil at about 78 degrees Celsius (172 degrees Fahrenheit). Mercury is a good conductor of heat. 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. Expansion of mercury is uniform along the whole range of temperature. Mercury is a good conductor of heat. What is the primary reason why liquid mercury (Hg) has been commonly used in thermometers for more than a century? Mercury is not easily vaporized even at low temperatures. for a small change of temperature, the expansion of mercury is quite large. Relationships: ‘Romantic Burn-Outs’ Exist: And Here Are The Signs! Laboratories are often dependent upon the ability to measure temperatures and pressures. However, it freezes at – 39 Celsius, so Mercury cannot be used below this temperature. The alcohol thermometer or spirit thermometer is an alternative to the mercury-in-glass thermometer and has similar functions. Mercury, for instance, becomes a solid at -38.83 degrees Celsius (-37.89 degrees Fahrenheit). 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Why Mercury Is Used In The Thermometer The role of a thermometer is an important one, and when used it home it can be the one diagnostic tool that tells us whether we’re sick or not. 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. 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. 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