Mercury has high melting and boiling points making it a liquid over a broad range of temperature. Since it is a metal, it has a stable coefficient of expansion hence it expands uniformly and noticeably for a slight change of temperature.
Why do we use mercury or alcohol as thermometric liquids?
mercury and alcohol is used in thermometer because they expand at a fixed rate when it is heated , hence a slight change in temperature will increase the expansion a long way up the tube..
What is the principle of mercury thermometer?
Mercury thermometers are based on the principle that liquids expand when heated and contract when cooled. So, when the temperature increases, the mercury expands and rises up the tube and when the temperature decreases it contracts and does the opposite.
What happens if you break a mercury thermometer?
If you break a mercury thermometer or light bulb, a small amount of liquid mercury may spill out. Liquid mercury can separate into small beads, which can roll some distance away. The mercury may also evaporate into vapour. However, this small amount of mercury is extremely unlikely to cause problems for your health.
What are the advantages of mercury thermometer?
Advantages. It is a good conductor of heat and hence, can measure even high temperatures. It gives results quickly – has a fast response time. It expands linearly and less than alcohol and any other liquid.
Which expands more alcohol or mercury?
Mercury has a greater coefficient of thermal expansion than alcohol. This means a column of mercury will expand and rise more than a column of alcohol for the same temperature change. As a result, you can get finer readings with mercury.
Why do they use alcohol instead of water in thermometers?
Alcohol thermometers are used rather than mercury thermometers in very cold regions because alcohol has a lower freezing point than mercury. Pure ethanol freezes at -115 degrees C, while mercury freezes at -38 degrees C. Thermometers rely upon thermal expansion of the liquid in a bulb at the base of a thin glass tube.
Why is water not used as a thermometric liquid?
A. higher freezing point and low boiling point than other thermometric liquids. Therefore water is having a high boiling point. …
Is it illegal to have a mercury thermometer?
In 2001, California passed the California Mercury Reduction Act of 2001 (SB 633 – Sher). … The law also prohibited the sale or supply of mercury fever thermometers after July 2002. Mercury thermostats were banned from sale in California in January 2006.
Can you suggest alternatives to mercury thermometers?
There are numerous alternatives to mercury thermometers. … But increasingly, selecting an alternative to Hg is chiefly a matter of choosing among one of the three sensor types used in digital thermometry: platinum resistance (PRT), thermistor, and thermocouple.
What are the advantages of using mercury?
Advantages of mercury are:
- It is opaque and shining. …
- It does not wet the glass.
- It has a low freezing point and a high boiling point. …
- It is a good conductor of hest, so it quickly absorbs heat to attain the temperature of the object.
- It has a wide range of temperature expansion.
What is thermometric fluid?
(thermodynamics) A fluid that has properties, such as a large and uniform thermal expansion coefficient, good thermal conductivity, and chemical stability, that make it suitable for use in a thermometer.
Under what condition is it better to use alcohol instead of mercury in a thermometer?
Explanation: The freezing point of mercury is approx -39°C and that of alcohol is -114°C. Therefore, in areas of extreme cold conditions, alcohol thermometer is better to use than mercury thermometer.
Which liquid is used in a thermometer?
In a mercury thermometer, a glass tube is filled with mercury and a standard temperature scale is marked on the tube. With changes in temperature, the mercury expands and contracts, and the temperature can be read from the scale. Mercury thermometers can be used to determine body, liquid, and vapor temperature.
What is the difference between alcohol and mercury?
Main Difference – Alcohol vs Mercury Thermometers
A thermometer is a device that is used to measure the temperature. … The main difference between alcohol and mercury thermometer is that the bulb of mercury thermometer is filled with mercury whereas the bulb of alcohol thermometer is filled with an alcohol.
Why does alcohol expand more than mercury?
A substance that expands faster will also contract faster. Alcohol expands more than mercury because of its low density and volatile nature. … Alcohol is not poisonous like mercury so it is less hazardous. Alcohol thermometers can be used to measure lower temperatures than mercury thermometers.
What do alcohol and mercury have in common?
They both have thermal conductivity in common . they also share the property of water solubility which is lesly taken into account in terms of alcohol and water because they almost all liquid have this property .
What are the disadvantages of mercury?
What are the disadvantages of mercury?
- It cannot measure very low temperature, because its freezing point is high (-40ºC)
- Mercury is poisonous, so it harmful if its tube is broken.
- Its price is very high.
- display is harder to read.
- cannot be used for thermograph.
- slow response.
- fragile.
Why is mercury no longer used in thermometer?
The reason: Mercury released into the environment from a broken thermometer is highly poisonous. … So government and state agencies have mounted campaigns to end the use of thermometers that contain the liquid metal. Federal and state authorities have lobbied since 2002 for bans on medical mercury thermometers.
Is mercury thermometer more accurate than infrared?
The median difference between infrared tympanic and rectal mercury thermometry in the whole material was -0.5 degree C, but increased to -1.4 degrees C in a selected group with rectal temperature 38 degrees C or more. … In a clinical setting the infrared ear thermometer has a very low sensitivity for detecting fever.
Can u touch mercury?
Mercury is a very toxic or poisonous substance that people can be exposed to in several ways. If it is swallowed, like from a broken thermometer, it mostly passes through your body and very little is absorbed. If you touch it, a small amount may pass through your skin, but not usually enough to harm you.