What are the advantages of calibrating the standard temperat

What are the advantages of calibrating the standard temperature for the freezing point and boiling point? Try to find out the relationship of temperature measuring in the ambient pressure between the freezing point and the boiling temperature to the measurement. What is the disadvantage?

Solution

Solution

When the thermometer was ist invented there was no clear understanding of fixed temperature points. To further confuse the situation the skills required to make thermometer were not availabe. It was difficult to make a thermometer with a bore of consistent diameter along its length , meaning that no two thermometers were alike. It was only when people travelled wiht individual thermometers that they were able to confirm that the fixed point of water boiling and freezing were the same in different locations and the effects of altitude and air pressure were reconized. The boiling and freezing points of water were choosen as fixed points because they were easily achievable. Once the fixed point had been recognized and thermometer making skills had improved, the way was clear for a widely reconized temperature scale.

The main advantage for the freezing and boiling point is that they are easily achievable.

In farenheight 32 is the lowest point taken, this is the scale that would not fall zero below zero even when measuring the lowest possible temperature that could produce in the laboratory, a mixture of ice , salt and water .It is some thing suggested that farenheight divided his scale into 100 degrees using blood temperature and his lowest possible temperature as fixed points...this is not true .

As well as the boiling or melting point of a substance, the triple point of a substance can be use as a fixed point. This is the temperature at which that substance exists in its solid, liquid and gaseous state all at the same time.

The triple point of water is the most important fixed point on ITS-90 as it is the sole fixed point which is common to ITS-90 and the Kelvin Thermodynamic Temperature Scale.
In the Brannan Calibration Laboratory we regularly use the triple point of water to recalibrate thermometers for our customers - its temperature is 0.01°C ( 273.16K ) and it can be recreated with great accuracy.
To recreate the triple point conditions we use a high powered refrigeration unit and a triple point cell which has been made in accordance with the ITS-90 specifications.