This total includes thermostats used in residences, businesses, and industrial settings, including thermostats sold as stand-alone units … These non-mercury fever thermometers are just as good as mercury thermometers and much safer. It is a metal, so it’s a good conductor of heat. Most metals are good conductors of heat and they are solids at room temperature. Mercury thermometers can be used to determine body, liquid, and vapor temperature. Mercury does not stick to the glass surface. Relationships: ‘Romantic Burn-Outs’ Exist: And Here Are The Signs! 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. The mercury-in-glass or mercury thermometer was invented by physicist Daniel Gabriel Fahrenheit in Amsterdam (1714). 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. “A metal is full of bonds between the atoms that make it up,” explains Carter. However, they can measure a much greater temperature range than thermistors. 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. Many older thermometers contained mercury. However, ethanol boils at 78°C (172.4°F), which means its upper limit is much lower than mercury thermometers. The mercury thermometer, long a fixture in household medicine cabinets and industrial settings, is going the way of the horse and buggy. Electrical-resistance thermometers characteristically use platinum and, like thermistors, operate on the principle that electrical resistance varies with changes in temperature. Thermocouples are among the most widely used industrial thermometers. A barometer using water, for instance, would need to be 13.6 times taller than a mercury barometer to obtain the same pressure difference. 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. 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. Red dye is used to color the clear alcohol so that someone is able to easily read the thermometer. 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 thermometers can be used to decide the body, liquid, and vapor temperature. The Times of India News App for Latest Sunday Times News, Copyright © 2021 Bennett, Coleman & Co. Ltd. All rights reserved. Why is mercury dangerous? Mercury boils at 357°C, so, it can, therefore, be used to measure higher temperatures. 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. With changes in temperature, the mercury expands and contracts, and the temperature can be read from the scale. Why are mercury thermometers being replaced? Why is mercury used in thermometers despite being the poorest conductor of heat? The boiling point of water is 100oc. Mankind learned about thermodynamic temperature centuries after the first thermometer was invented. So it gives the correct temperature. So mercury level indicates the temperature as quickly as possible and accurately. The rest of the tube may be a vacuum, or it may be filled with nitrogen. Thermometer | Why is mercury used in thermometer | precautions using thermometer | PB Learning Hub A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). Digital thermometers work by using heat sensors that determine body temperature. 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. Liquid thermometers can be limited by the type of liquid used. Photo by Matteo Fusco on Unsplash. In a thermometer, a glass bulb attached to a glass capillary tube is filled with mercury. The space above the mercury may be filled with nitrogengas or it may b… They expand and contract depending on the pressure or temeperature of their environment. A thermometer has two important elements: (1) a temperature sensor (e.g. The alcohol thermometer or spirit thermometer is an alternative to the mercury-in-glass thermometer and has similar functions. Mercury is particularly harmful to fetuses, infants and children. j) Mercury has a low latent heat for evaporation © copyright 2020 QS Study. 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. Mercury is a good conductor of heat. For reprint rights: Times Syndication Service. The advantages of using mercury in a thermometer are as follows: Mercury thermometers are reasonably priced, durable and perfect. Alcohols, such as ethanol, boil at about 78 degrees Celsius (172 degrees Fahrenheit). Mercury is opaque and bright, so the movement of mercury inside the capillary tube is easily visible. Mercury's Use: Despite mercury being toxic to humans in its natural form, it has a variety of everyday uses. 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. It can be found in meteorological equipment like thermometers and barometers. Why are we using Mercury in thermometer, reasons are followed:. However, it freezes at – 39 Celsius, so Mercury cannot be used below this temperature. There are a number of different model types, sizes, and specifications, but the general operating principle is about the same in all cases. 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. When two bodies touch, their temperature adjusts, which means that the colder gets warmer, the warmer gets colder. Several states prohibit the sale of mercury-containing thermometers. Most metals are good conductors of heat and they are solids at room temperature. Mercury is the only one which is liquid at room temperature, which makes it easy to work with. Actually, we try to avoid it these days. 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. Mercury is used in a thermometer because it has a lot of advantages. It's used in thermometers because it has high coefficient of expansion. 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. Mercury, for instance, becomes a solid at -38.83 degrees Celsius (-37.89 degrees Fahrenheit). In a mercury thermometer, a glass tube is filled with mercury and a usual temperature scale is marked on the tube. 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. Infrared (ear) thermometers may be used as an alternative to mercury fever thermometers. Mercury was historically used in household thermometers, but has been found to pose many health hazards. for a small change of temperature, the expansion of mercury is quite large. 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 … “What determines a material’s melting point has everything to do with the energy associated with the bonds. Liquid thermometers can be limited by the type of liquid used. Mercury is the only one in liquid state at room temperature. Several states prohibit the sale of mercury-containing thermometers. That is why mercury is used in thermometers. All rights reserved. Mercury may be found in fever, basal, scientific, industrial and cooking thermometers. What is mercury? Mercury thermometers cannot measure temperatures below this point. Mercury expands as the temperature increases, thus raising the reading, while decreasing temperatures contract the mercury, lowering the reading. Alcohols, such as ethanol, boil at about 78 degrees Celsius (172 degrees Fahrenheit). However, it freezes at – 39 Celsius, so Mercury cannot be used below this temperature. Broken mercury-filled thermometers … Continued 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. While mercury thermometers are safe when used correctly, they pose significant risks when they break or if disposed of improperly. 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 … Mercury thermometers will become a thing of the past in hospitals within the next few years if trends favouring alternative devices continue. With changes in temperature, the mercury expands and contracts, and the temperature can be read from the scale. What is the primary reason why liquid mercury (Hg) has been commonly used in thermometers for more than a century? Metallic mercury is toxic, and also expensive. The increase of mercury is steady or linear to the changes of the heat, except for actual high temperature. f) Mercury looks nice and shiny. Today, mercury is used for the manufacture of industrial chemicals and for electrical and electronic applications. 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. ©Pxhere. h) Mercury expands a lot with temperature. Therefore, initially, thermometers defined temperatures. Will the replacement of mercury thermometers be problematic? It will not enlarge when it solidifies, therefore, it doesn’t fracture the glass tube of the thermometer. Dangers of Mercury Mercury is a very dense element that is the only metal to exist as a liquid at room temperature. Today, mercury is used for the manufacture of industrial chemicals and for electrical and electronic applications. Unlike the mercury-in-glass thermometer, the contents of an alcohol thermometer are less toxic and will evaporate quickly. Mercury is not easily vaporized even at low temperatures. However, it freezes at – 39 Celsius, so Mercury cannot be used below this temperature. Why are mercury thermometers being replaced? Hence it is convenient to make marks on the thermometer surface. It has a high electrical conductivity and it expands and contracts evenly with changes in temperature. Laboratories are often dependent upon the ability to measure temperatures and pressures. The alcohol thermometer or spirit thermometer is an alternative to the mercury-in-glass thermometer and has similar functions. Daniel Gabriel Fahrenheit used alcohol in thermometers in the 1700s. It has a high electrical conductivity and it expands and contracts evenly with changes in temperature. Thermometers containing mercury can be easily identified by the colour of the material in the bulb. One of them is fixed. Digital or spirit-filled (red) thermometers are a safer alternative. Mercury is well documented as a toxic, environmentally-persistent substance. It comes in a few forms. However, they can measure a much greater temperature range than thermistors. New electronic thermometers and those that use a red dye and alcohol mixture are much easier to read and safer to use. The first thermometers manufactured contained water but the fact that water freezes at 32 degrees Fahrenheit led manufacturers to switch to mercury. Mercury thermometers can be used to determine body, liquid, and vapor 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. Historically, mercury thermometers have been used for nearly all temperature measurements because of their accuracy and low cost. g) Mercury is not an expensive metal. Wilfrid Francis, Martin C. Peters, in Fuels and Fuel Technology (Second Edition), 1980. Historically, mercury thermometers have been used for nearly all temperature measurements because of their accuracy and low cost. A mercury thermometer is a tool used to measure temperature. 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Mercury thermometers are now being replaced by digital thermometers. 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. 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. 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 mercury thermometer, long a fixture in household medicine cabinets and industrial settings, is going the way of the horse and buggy. Consider discontinuing the use of thermometers containing mercury if it is used for cooking or is a clinical thermometer. Red dye is used to color the clear alcohol so that someone is able to easily read the thermometer. This continues until they are warm. 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. With changes in temperature, the mercury expands and contracts and the temperature can be read from the scale. 5. Elemental (metallic) mercury is a shiny, silver-colored liquid products, including lots of things used in schools. It also has a high boiling point which makes it very suitable to measure higher temperatures. When used correctly, the digital thermometer is accurate enough to meet daily needs and safer than the mercury thermometer. 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 thermometers are being phased out in the US. Mercury does not damp glass, this leads to an erroneous reading when the thread is falling. Since mercury is highly toxic, using them in food or in the body is discouraged. 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.