Alcohol is less expensive and the compounds formed from oxides of Mercury are poisonous while alcohol is less problematic.
Mercury thermometers have advantages over alcohol thermometers. The liquid is visible making the results easy to read. It expands at a regular interval. It measures temperature quickly and accurately.
why is the purpose of using coloured alcohal instead of usin any other compound why use of alcohal is preferred over mercury in thermometers
At time mercury was used to extract metallic gold from gold ore. The ore was crushed to powder, and washed over a copper sheet covered in mercury. The gold would combine with the mercury, and be recovered by distilling the mercury. This was very dangerous due to the poisonous nature of mercury- and it only captured about 15% of the gold. It is no longer used in gold mining.
I consider that this preference is only illusory.
At one time, mercury WAS used to extract gold from gold ore. The rock was crushed, and washed over a copper sheet coated with mercury. Gold forms an amalgam with mercury, and some of the gold would be trapped in the mercury. The mercury would be scraped from the copper, and distilled, leaving behind the gold. Other processes are used today.
Mercury thermometers have advantages over alcohol thermometers. The liquid is visible making the results easy to read. It expands at a regular interval. It measures temperature quickly and accurately.
what are the qualities of mercury over alchoholic as thermometric liquid
why is the purpose of using coloured alcohal instead of usin any other compound why use of alcohal is preferred over mercury in thermometers
I assume you mean "alcohol". One important disadvantage of mercury is that it is very toxic. Ethanol (the common alcohol) is toxic as well, but not quite as harmful as mercury. Specifically, inhaling a small amount of its vapor won't get you sick.
Mercury is the only metal that remains liquid at room temperature and it expands and contracts evenly over a large temperature range of -40to +300 degrees. Unfortunately it is toxic when the thermometer breaks and so alcohol is replacing Mercury for every day -10 to 100degree C thermometers as used in school labs. Electronic temperature sensors,like thermocouples, are taking over for higher temperatures.
Mercury is very toxic and can cause nerve damage and once it enters the body is just about impossible to get out. Alcohol is a much less hazardous substance. Even though it can be toxic, the body easily breaks it down in low doses. . Also, alcohol is commercially more abundant and less expensive than mercury.
Mercury is a toxic heavy metal. The possibility of breakage and the subsequent release of mercury into the body, or into the environment, means that mercury usage has gradually been phased out in consumer thermometers. Laboratory thermometers often still contain mercury, since it's useful over a wide range of temperatures. This isn't so critical in medical thermometers, since the body temperature of someone who isn't actually dead is almost certainly going to be no more than 10 degrees from 37 Celcius.
Digital thermometers should have a plastic sleeve, but even with that, you should use an alcohol swab to thoroughly wet, rub it and allow it to air dry after each use. Some of the digitals will have battery and "mother board" problems if you wash them in soapy water. The old-timey mercury thermometers and modern non-digital thermometers can be soaked in alcohol over night or washed with warm soapy water and then swabbed with alcohol, allowed to dry and returned to their cases. Since you can get digital thermometers for less than 10.00, it is a good idea to have a thermometer for each person in your family....and if you are really germ-phobic you can replace them after every illness...but that is overkill, IMO.
Yes. Most standard lab thermometers are either alcohol or mercury filled.
Early thermometers, dating back over two hundred years BC (BCE), were made using air and water. Later, in the time of Galileo (16-1700s AD or CE), these devices were refined;Galileo used glass spheres containing alcohol to measure temperature, and today working 'Galileo' thermometers using alcohol-filled spheres suspended in water are available from retail outlets, mainly for ornamental use and as curiosities. They are attractive, though not to be considered especially accurate, and are more properly described as thermoscopes.The original commercially-available thermometers contained mercury. The mercury thermometer was first made by Prussian-born physicist and glass-blower, Daniel Fahrenheit in 1724. The specifically clinical thermometer was invented in 1866 by British physician, Sir Thomas Albutt.Electronic thermometers are commonly used now for clinical, industrial and domestic purposes; these produce a digital display and are safer and more accurate than the mercury-in-glass thermometers.The sale of mercury thermometers is banned in many countries and US states; this is causing quite a few problems because they are still required under many industrial and government standards worldwide.Resistance temperature detectors (RTDs) contain platinum, either in the form of wire or film. These thermometers also have a digital display.RTDs are highly accurate and are frequently used in testing the results of other thermometers to industrial standards.
Rather ironically, it depends on the temperatures involved. Most thermometers use mercury. Partly, this is because the silver colour of the mercury make it easy to read, but mainly because they work over a useful range of temperatures for everyday use. However, one problem with mercury is that its melting point is -38oC; so below that temperature the thermometer would freeze - this makes it unsuitable for use in very cold environments. Alchohol thermometers (usually ethanol is used) work from around -115oC, so they are used in low temperature environments - the disadvantage with alcohol is that it vaporises at 78oC so it isn't useful in very hot environments.
- Read the temperature over the meniscus (for mercury thermometers)- Avoid the parallaxe error- Respect the depth of immersion thermometer- Don't use thermometers with defects (ex. air bubbles)- Wait a reasonable time the setting of indication for the thermometer