The increase of mercury is steady or linear to the changes of the heat, except for actual high temperature. What is the primary reason why liquid mercury (Hg) has been commonly used in thermometers for more than a century? You might remember it best from its use in glass thermometers. Many older thermometers contained mercury. Will the replacement of mercury thermometers be problematic? Today, mercury is used for the manufacture of industrial chemicals and for electrical and electronic applications. Table 1 presents the total amount of mercury contained in mercury thermostats sold in the U.S. in years 2001, 2004, and 2007. 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. The increase of mercury is steady or linear to the changes of the heat, except for actual high temperature. People tend to associate mercury with its silvery liquid form - perhaps found in old thermometers. The first thermometers, however, weren’t thermos or heat measurers, but thermo-scopes, devices that merely signaled whether the temperature was high or low. Dangers of Mercury Mercury is a very dense element that is the only metal to exist as a liquid at room 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. Somewhere in the middle is mercury, which stays in a liquid state until its temperature drops to -40°. A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). Several states prohibit the sale of mercury-containing thermometers. Metallic mercury is toxic, and also expensive. 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. The increase of mercury is steady or linear to the changes of the heat, except for actual high temperature. Wilfrid Francis, Martin C. Peters, in Fuels and Fuel Technology (Second Edition), 1980. “A metal is full of bonds between the atoms that make it up,” explains Carter. 5. Hence it is convenient to make marks on the thermometer surface. Mercury expands as the temperature increases, thus raising the reading, while decreasing temperatures contract the mercury, lowering the reading. 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 … 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 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. Red dye is used to color the clear alcohol so that someone is able to easily read the thermometer. When used correctly, the digital thermometer is accurate enough to meet daily needs and safer than the mercury thermometer. In a thermometer, a glass bulb attached to a glass capillary tube is filled with mercury. Mercury thermometers are used in: power plants and piping; chemical tanks; heating and cooling equipment; canneries; ships; paint kettles etc. It can be found in meteorological equipment like thermometers and barometers. ��� Shambhavi Tambulwadkar, recd via e-mail, Dark day in the history of US Capitol: Mike Pence, Kashmera's pool video in a bikini is breaking the internet, Rehan Chaudhary thanks the musical team, after recording 'Dhuandhaar' songs. Mercury is well documented as a toxic, environmentally-persistent substance. While mercury thermometers are safe when used correctly, they pose significant risks when they break or if disposed of improperly. Since mercury is highly toxic, using them in food or in the body is discouraged. 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. Mercury is well documented as a toxic, environmentally-persistent substance. With changes in temperature, the mercury expands and contracts, and the temperature can be read from the scale. For most applications, alternatives to mercury-containing thermometers are available. 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). h) Mercury expands a lot with 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. Alcohols, such as ethanol, boil at about 78 degrees Celsius (172 degrees Fahrenheit). These devices weren’t calibrated to a standard scale; they would just make crude or vague assessments.The in… However, it freezes at – 39 Celsius, so Mercury cannot be used below this temperature. Thermocouples are among the most widely used industrial thermometers. The space above the mercury may be filled with nitrogengas or it may b… However, they can measure a much greater temperature range than thermistors. It is used in thermometers because it has a high coefficient of expansion. 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. However, it freezes at – 39 Celsius, so Mercury cannot be used below this temperature. The first thermometers manufactured contained water but the fact that water freezes at 32 degrees Fahrenheit led manufacturers to switch to mercury. 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. 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, for instance, becomes a solid at -38.83 degrees Celsius (-37.89 degrees Fahrenheit). Expansion of mercury is uniform along the whole range of temperature. Also, it has a shiny appearance and doesn't stick to the glass surface of glass. Hence, the slightest change in temperature is notable when it's used in a thermometer. When two bodies touch, their temperature adjusts, which means that the colder gets warmer, the warmer gets colder. 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. Dangers of Mercury Mercury is a very dense element that is the only metal to exist as a liquid at room 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. Mercury thermometers cannot measure temperatures below this point. Its stage indicates the temperature as rapidly as potential and perfectly. There are a number of different model types, sizes, and specifications, but the general operating principle is about the same in all cases. © copyright 2020 QS Study. It has a high electrical conductivity and it expands and contracts evenly with changes in temperature. Broken mercury-filled thermometers … Continued Imagine two thin wires inside the capillary of your thermometer. Mankind learned about thermodynamic temperature centuries after the first thermometer was invented. It is a metal, so it’s a good conductor of heat. What is mercury? 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. The mercury thermometer, long a fixture in household medicine cabinets and industrial settings, is going the way of the horse and buggy. 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. Alcohols, such as ethanol, boil at about 78 degrees Celsius (172 degrees Fahrenheit). 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. Mercury is particularly harmful to fetuses, infants and children. It's used in thermometers because it has high coefficient of expansion. 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. Mercury has much better conductivity and expands quickly, and thus indicates a temperature adjust swiftly. Mercury does not damp glass, this leads to an erroneous reading when the thread is falling. 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Thermometer | Why is mercury used in thermometer | precautions using thermometer | PB Learning Hub 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. Liquid thermometers can be limited by the type of liquid used. Mercury has a … 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. It's used in thermometers because it has high coefficient of expansion. With changes in temperature, the mercury expands and contracts and the temperature can be read from the scale. Mercury does not stick to the glass surface. Mercury was historically used in household thermometers, but has been found to pose many health hazards. “What determines a material’s melting point has everything to do with the energy associated with the bonds. Mercury has been replaced largely by alcohol for use in thermometers. They expand and contract depending on the pressure or temeperature of their environment. Actually, we try to avoid it these days. Mercury is a good conductor of heat. For most applications, alternatives to mercury-containing thermometers are available. 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 mercury thermometer, long a fixture in household medicine cabinets and industrial settings, is going the way of the horse and buggy. Why is mercury used in thermometers despite being the poorest conductor of heat? Mercury is opaque and bright, so the movement of mercury inside the capillary tube is easily visible. Electrical-resistance thermometers characteristically use platinum and, like thermistors, operate on the principle that electrical resistance varies with changes in temperature. Mercury may be found in fever, basal, scientific, industrial and cooking thermometers. Relationships: ‘Romantic Burn-Outs’ Exist: And Here Are The Signs! Digital thermometers work by using heat sensors that determine body temperature. 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. Mercury is the only one in liquid state at room temperature. Infrared (ear) thermometers may be used as an alternative to mercury fever thermometers. Photo by Matteo Fusco on Unsplash. i) Mercury has very high density compared to other liquids. However, they can measure a much greater temperature range than thermistors. g) Mercury is not an expensive metal. Mercury thermometers can be used to determine body, liquid, and vapor temperature. New electronic thermometers and those that use a red dye and alcohol mixture are much easier to read and safer to use. Most metals are good conductors of heat and they are solids at room temperature. In a mercury thermometer, a glass tube is filled with mercury and a standard temperature scale is marked on the tube. Mercury boils at 357°C, so, it can, therefore, be used to measure higher temperatures. Mercury thermometers are being phased out in the US. 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. Will the replacement of mercury thermometers be problematic? j) Mercury has a low latent heat for evaporation Unlike the mercury-in-glass thermometer, the contents of an alcohol thermometer are less toxic and will evaporate quickly. It has a high electrical conductivity and it expands and contracts evenly with changes in temperature. Daniel Gabriel Fahrenheit used alcohol in thermometers in the 1700s. Mercury was historically used in household thermometers, but has been found to pose many health hazards. Mercury is used in thermometers. Mercury is the only one in a liquid state at room temperature. This means that it reacts quickly to changes in temperature. Laboratories are often dependent upon the ability to measure temperatures and pressures. Mercury thermometers can be used to determine body, liquid, and vapor temperature. However, they present many safety and environmental hazards. Most metals are good conductors of heat and they are solids at room 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. 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. 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. Other Corrections 1 The Thermometer Correction. That is why mercury is used in thermometers. Mercury thermometers are now being replaced by digital thermometers. These thermometers are used in households, laboratory experiments, and industrial applications. Therefore, initially, thermometers defined temperatures. Thermocouples are among the most widely used industrial thermometers. 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. This total includes thermostats used in residences, businesses, and industrial settings, including thermostats sold as stand-alone units … Unfortunately, this measurement is not without hazard. Red dye is used to color the clear alcohol so that someone is able to easily read the thermometer. Today, mercury is used for the manufacture of industrial chemicals and for electrical and electronic applications. People tend to associate mercury with its silvery liquid form - perhaps found in old thermometers. A thermometer has two important elements: (1) a temperature sensor (e.g. for a small change of temperature, the expansion of mercury is quite large. Mercury expands as the temperature increases, thus raising the reading, while decreasing temperatures contract the mercury, lowering the reading. 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. A: Mercury has been used in heat and pressure measuring instruments since the first intruments were made.. Metals are very good conducters of heat. For reprint rights: Times Syndication Service. The thermometer usually has a small reserve of liquid mercury in … A mercury thermometer is a tool used to measure temperature. Mercury thermometers will become a thing of the past in hospitals within the next few years if trends favouring alternative devices continue. Unfortunately, mercury is toxic and it is replaced almost everywhere. Mercury is a metal found naturally in the environment. Digital or spirit-filled (red) thermometers are a safer alternative. Historically, mercury thermometers have been used for nearly all temperature measurements because of their accuracy and low cost. Mercury is used in a thermometer because it has a lot of advantages. A barometer using water, for instance, would need to be 13.6 times taller than a mercury barometer to obtain the same pressure difference. Why are mercury thermometers being replaced? The alcohol thermometer or spirit thermometer is an alternative to the mercury-in-glass thermometer and has similar functions. This continues until they are warm. 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. Thermometers that check body temperature in the ear, across the forehead, or have a digital display do not contain mercury. The boiling point of water is 100oc. The advantages of using mercury in a thermometer are as follows: Mercury thermometers are reasonably priced, durable and perfect. In a mercury thermometer, a glass tube is filled with mercury and a usual temperature scale is marked on the tube. Several states prohibit the sale of mercury-containing thermometers. 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. Why are mercury thermometers being replaced? Mercury's Use: Despite mercury being toxic to humans in its natural form, it has a variety of everyday uses. So it can move freely inside the capillary glass tube. So it gives the correct temperature. Mercury thermometers cannot measure temperatures below this point. So mercury level indicates the temperature as quickly as possible and accurately. Mercury boils at 357°C, so, it can, therefore, be used to measure higher temperatures. Mercury is less volatile. When used correctly, the digital thermometer is accurate enough to meet daily needs and safer than the mercury thermometer. Mercury thermometers can be used to decide the body, liquid, and vapor temperature. 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. Electrical-resistance thermometers characteristically use platinum and, like thermistors, operate on the principle that electrical resistance varies with changes in temperature. Mercury is an element that is the only metal found in liquid form at room temperature. ©Pxhere. Mercury is an element that is the only metal found in liquid form at room 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 … All rights reserved. It comes in a few forms. 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