Thermometers that check body temperature in the ear, across the forehead, or have a digital display do not contain mercury. Mercury has been replaced largely by alcohol for use in thermometers. In a mercury thermometer, a glass tube is filled with mercury and a standard temperature scale is marked on the tube. Alcohols, such as ethanol, boil at about 78 degrees Celsius (172 degrees Fahrenheit). Mercury thermometers are now being replaced by digital thermometers. The mercury is the red substance in the thermometer that rises when you put it in your mouth. i) Mercury has very high density compared to other liquids. Thermometers that check body temperature in the ear, across the forehead, or have a digital display do not contain mercury. Mercury is used in thermometers. They can be used to take temperature readings in the mouth, rectum, or armpit.. Mercury is particularly harmful to fetuses, infants and children. Why is mercury dangerous? The first thermometers manufactured contained water but the fact that water freezes at 32 degrees Fahrenheit led manufacturers to switch to mercury. While mercury thermometers are safe when used correctly, they pose significant risks when they break or if disposed of improperly. That is why mercury is used in thermometers. The increase of mercury is steady or linear to the changes of the heat, except for actual high temperature. Unfortunately, this measurement is not without hazard. for a small change of temperature, the expansion of mercury is quite large. 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. Today, mercury is used for the manufacture of industrial chemicals and for electrical and electronic applications. Several states prohibit the sale of mercury-containing thermometers. So it gives the correct temperature. Mercury has much better conductivity and expands quickly, and thus indicates a temperature adjust swiftly. 6. Digital or spirit-filled (red) thermometers are a safer alternative. 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. Mercury is less volatile. These thermometers are used in households, laboratory experiments, and industrial applications. Mercury thermometers will become a thing of the past in hospitals within the next few years if trends favouring alternative devices continue. Why are we using Mercury in thermometer, reasons are followed:. The increase of mercury is steady or linear to the changes of the heat, except for actual high temperature. Historically, mercury thermometers have been used for nearly all temperature measurements because of their accuracy and low cost. Mercury thermometers are used in: power plants and piping; chemical tanks; heating and cooling equipment; canneries; ships; paint kettles etc. Wilfrid Francis, Martin C. Peters, in Fuels and Fuel Technology (Second Edition), 1980. Daniel Gabriel Fahrenheit used alcohol in thermometers in the 1700s. Mercury is not easily vaporized even at low temperatures. It has a high electrical conductivity and it expands and contracts evenly with changes in temperature. Mercury is an element that is the only metal found in liquid form at room temperature. It's used in thermometers because it has high coefficient of expansion. Mercury expands as the temperature increases, thus raising the reading, while decreasing temperatures contract the mercury, lowering the reading. However, it freezes at 39 Celsius, so Mercury cannot be used below this temperature. Pxhere. 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). The increase of mercury is steady or linear to the changes of the heat, except for actual high temperature. copyright 2020QS Study. The space above the mercury may be filled with nitrogengas or it may b Why are mercury thermometers being replaced? Mercury is well documented as a toxic, environmentally-persistent substance. 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. It has a high electrical conductivity and it expands and contracts evenly with changes in temperature. Actually, we try to avoid it these days. Red dye is used to color the clear alcohol so that someone is able to easily read the thermometer. The thermometer usually has a small reserve of liquid mercury in 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 was historically used in household thermometers, but has been found to pose many health hazards. The rest of the tube may be a vacuum, or it may be filled with nitrogen. Its stage indicates the temperature as rapidly as potential and perfectly. For reprint rights: Times Syndication Service. 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. This means that it reacts quickly to changes in temperature. Mercury does not stick to the glass surface. For most applications, alternatives to mercury-containing thermometers are available. The alcohol thermometer or spirit thermometer is an alternative to the mercury-in-glass thermometer and has similar functions. Electrical-resistance thermometers characteristically use platinum and, like thermistors, operate on the principle that electrical resistance varies with changes in temperature. Mercury is a good conductor of heat. Mercury is a good conductor of heat. 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. It is used in thermometers because it has a high coefficient of expansion. It is a metal, so its a good conductor of heat. g) Mercury is not an expensive metal. This total includes thermostats used in residences, businesses, and industrial settings, including thermostats sold as stand-alone units A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). The mercury thermometer, long a fixture in household medicine cabinets and industrial settings, is going the way of the horse and buggy. The mercury-in-glass or mercury thermometer was invented by physicist Daniel Gabriel Fahrenheit in Amsterdam (1714). People tend to associate mercury with its silvery liquid form - perhaps found in old thermometers. Red dye is used to color the clear alcohol so that someone is able to easily read the thermometer. The other wire is can move along a threaded rod. Mankind learned about thermodynamic temperature centuries after the first thermometer was invented. Mercury boils at 357C, so, it can, therefore, be used to measure higher temperatures. It will not enlarge when it solidifies, therefore, it doesnt fracture the glass tube of the thermometer. In a thermometer, a glass bulb attached to a glass capillary tube is filled with mercury. Most metals are good conductors of heat and they are solids 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. However, it freezes at 39 Celsius, so Mercury cannot be used below this temperature. One of them is fixed. Mercury may be found in fever, basal, scientific, industrial and cooking thermometers. Consider discontinuing the use of thermometers containing mercury if it is used for cooking or is a clinical thermometer. Mercury is the only one in liquid state at room temperature. Mercury does not damp glass, this leads to an erroneous reading when the thread is falling. Metallic mercury is toxic, and also expensive. It comes in a few forms. 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. This continues until they are warm. Elemental (metallic) mercury is a shiny, silver-colored liquid products, including lots of things used in schools. Laboratories are often dependent upon the ability to measure temperatures and pressures. j) Mercury has a low latent heat for evaporation Mercury is the only one in liquid state at room temperature. Mercury thermometers cannot measure temperatures below this point. f) Mercury looks nice and shiny. Mercury Hazards Mercury has been used in the measurement of atmospheric pressures and temperatures since the mid 1600s. Thermometers containing mercury can be easily identified by the colour of the material in the bulb. Mercury boils at 357C, so, it can, therefore, be used to measure higher temperatures. 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. Hence, the slightest change in temperature is notable when it's used in a thermometer. Many older thermometers contained mercury. Other Corrections 1 The Thermometer Correction. Infrared (ear) thermometers may be used as an alternative to mercury fever thermometers. These non-mercury fever thermometers are just as good as mercury thermometers and much safer. 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. There are a number of different model types, sizes, and specifications, but the general operating principle is about the same in all cases. Mercury is well documented as a toxic, environmentally-persistent substance. 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 A thermometer has two important elements: (1) a temperature sensor (e.g. You might remember it best from its use in glass thermometers. Most metals are good conductors of heat and they are solids at room temperature. Mercury has been frequently used in thermometers because it remains in liquid form throughout a wide range of temperatures: -37.89 degrees Fahrenheit to 674.06 degrees Fahrenheit. Will the replacement of mercury thermometers be problematic? 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. 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 dont overturn your regulator, The vast wetlands of Els Eels are the most recorded at the bottom of the ocean. What is mercury? Mercury boils at 357C, so, it can, therefore, be used to measure higher temperatures. 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 were sick or not. Mercury is a metal found naturally in the environment. Several states prohibit the sale of mercury-containing thermometers. With changes in temperature, the mercury expands and contracts, and the temperature can be read from the scale. Why is mercury used in thermometers despite being the poorest conductor of heat? Will the replacement of mercury thermometers be problematic? h) Mercury expands a lot with temperature. Photo by Matteo Fusco on Unsplash. A metal is full of bonds between the atoms that make it up, explains Carter. 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. Digital thermometers work by using heat sensors that determine body temperature. Mercury is used in a thermometer because it has a lot of advantages. These non-mercury fever thermometers are just as good as mercury thermometers and much safer. 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). Mercury thermometers are being phased out in the US. For most applications, alternatives to mercury-containing thermometers are available. When used correctly, the digital thermometer is accurate enough to meet daily needs and safer than the mercury thermometer. With changes in temperature, the mercury expands and contracts, and the temperature can be read from the scale. Liquid thermometers can be limited by the type of liquid used. So mercury level indicates the temperature as quickly as possible and accurately. Mercury, for instance, becomes a solid at -38.83 degrees Celsius (-37.89 degrees Fahrenheit). Thermometer | Why is mercury used in thermometer | precautions using thermometer | PB Learning Hub Broken mercury-filled thermometers Continued Unlike the mercury-in-glass thermometer, the contents of an alcohol thermometer are less toxic and will evaporate quickly. All rights reserved. The Times of India News App for Latest Sunday Times News, Copyright 2021 Bennett, Coleman & Co. Ltd. All rights reserved. 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. Dangers of Mercury Mercury is a very dense element that is the only metal to exist as a liquid at room temperature. Thermocouples are among the most widely used industrial thermometers. Also, it has a shiny appearance and doesn't stick to the glass surface of glass. People tend to associate mercury with its silvery liquid form - perhaps found in old thermometers. When two bodies touch, their temperature adjusts, which means that the colder gets warmer, the warmer gets colder. Why are mercury thermometers being replaced? A mercury thermometer is a tool used to measure temperature. 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. In a mercury thermometer, a glass tube is filled with mercury and a usual temperature scale is marked on the tube. Relationships: Romantic Burn-Outs Exist: And Here Are The Signs! Today, mercury is used for the manufacture of industrial chemicals and for electrical and electronic applications. Thermocouples are among the most widely used industrial thermometers. However, ethanol boils at 78C (172.4F), which means its upper limit is much lower than mercury thermometers. Mercury thermometers can be used to decide the body, liquid, and vapor temperature. The first thermometers, however, werent thermos or heat measurers, but thermo-scopes, devices that merely signaled whether the temperature was high or low. So it can move freely inside the capillary glass tube. Mercury is the only one which is liquid at room temperature, which makes it easy to work with. With changes in temperature, the mercury expands and contracts and the temperature can be read from the scale. The alcohol thermometer or spirit thermometer is an alternative to the mercury-in-glass thermometer and has similar functions. 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. Table 1 presents the total amount of mercury contained in mercury thermostats sold in the U.S. in years 2001, 2004, and 2007. 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 cannot measure temperatures below this point. 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. It also has a high boiling point which makes it very suitable to measure higher temperatures. 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 A: Mercury has been used in heat and pressure measuring instruments since the first intruments were made.. Metals are very good conducters of heat. Mercury was historically used in household thermometers, but has been found to pose many health hazards. 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. What is the primary reason why liquid mercury (Hg) has been commonly used in thermometers for more than a century? Mercury thermometers can be used to determine body, liquid, and vapor temperature. Liquid thermometers can be limited by the type of liquid used. Historically, mercury thermometers have been used for nearly all temperature measurements because of their accuracy and low cost. Unlike the mercury-in-glass thermometer, the contents of an alcohol thermometer are less toxic and will evaporate quickly. Mercury, for instance, becomes a solid at -38.83 degrees Celsius (-37.89 degrees Fahrenheit). However, they present many safety and environmental hazards. It can be found in meteorological equipment like thermometers and barometers. 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. 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. However, they can measure a much greater temperature range than thermistors. Therefore, initially, thermometers defined temperatures. Expansion of mercury is uniform along the whole range of temperature. Imagine two thin wires inside the capillary of your thermometer. Mercury is opaque and bright, so the movement of mercury inside the capillary tube is easily visible. Unfortunately, mercury is toxic and it is replaced almost everywhere. Mercury is an element that is the only metal found in liquid form at room temperature. It can be found in meteorological equipment like thermometers and barometers. Mercury thermometers can be used to determine body, liquid, and vapor temperature. They expand and contract depending on the pressure or temeperature of their environment. Dangers of Mercury Mercury is a very dense element that is the only metal to exist as a liquid at room temperature. When used correctly, the digital thermometer is accurate enough to meet daily needs and safer than the mercury thermometer. The mercury thermometer, long a fixture in household medicine cabinets and industrial settings, is going the way of the horse and buggy. 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. New electronic thermometers and those that use a red dye and alcohol mixture are much easier to read and safer to use. What determines a materials melting point has everything to do with the energy associated with the bonds. However, it freezes at 39 Celsius, so Mercury cannot be used below this temperature. Electrical-resistance thermometers characteristically use platinum and, like thermistors, operate on the principle that electrical resistance varies with changes in temperature. A toxic, environmentally-persistent substance despite being the poorest conductor of why is mercury used in thermometer a thermometer is enough Level indicates the temperature as quickly as possible and accurately things used in households, laboratory,. Are much easier to read and safer than mercury thermometers being replaced by digital. The red substance in the mouth, rectum, or have a digital display do not contain mercury found pose. Manufacturers to switch to mercury fever thermometers are now being replaced by digital thermometers equipment like and. 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