Alcohol thermometers or spirit thermometers are an alternative to mercury thermometers in glass and have a similar function.
Unlike a mercury thermometer, the contents of an alcohol thermometer are less toxic and evaporate quickly.
Ethanol is widely used due to its low cost and relatively low risk of breakage.
A glass bubble containing an organic liquid is attached to a glass capillary tube and its end is closed with an expansion bubble.
The space above the liquid is a mixture of nitrogen and liquid vapor.
For the operating temperature range, the concave surface of the liquid is in the capillary tube.
As the temperature increases, the volume of the liquid increases and the concave surface moves upwards of the capillary tube.
The position of the concave surface shows the temperature in front of the recorded scale.
Depending on the manufacturer and the operating temperature range, the liquid used can be pure ethanol, toluene, kerosene or isoamyl acetate.
Because these liquids are clear, a blue or red color is added to make the liquid visible.
In order to create a background for reading the scale, half of the glass in which the capillary tube is placed is whitened or yellowed.
The efficiency range of the thermometer is adjusted by the boiling point of the liquid used.
If the thermometer is filled with ethanol, the upper limit of measurement is 78 ((4.172)), which makes it useful for measuring temperatures during the day, night and body temperature.
Ethanol-filled thermometers are preferable to mercury thermometers for measuring minimum temperatures in meteorology and can be used up to -70 ((-94)).
The physical limitation of a thermometer, or the ability of a thermometer to measure low temperature, depends on the freezing point of the liquid used.
Ethanol freezes at -11.49 ((-82 ℉ 174).
If an alcohol thermometer uses a combination of ethyl alcohol, toluene, and pentane, the lower temperature limit may be increased to -200-(℉ 328 برای) for measuring low temperatures.
However, measuring the temperature range from -200 تا to ℃78 depends to a large extent on the type of alcohol used.
Advantages and disadvantages of alcohol thermometer
An alcohol thermometer has advantages and disadvantages when compared to a mercury thermometer.
First, there are many types of alcohols that have different molecular formulas.
Methyl alcohol or methanol is the simplest type of alcohol that has only one carbon atom.
When carbon atoms are added to a molecular chain, the type of alcohol changes.
Ethanol is an alcohol with two carbon atoms. It is important to know what kind of alcohol is in the thermometer because the chemical properties of each type are different.
Here the most important properties of alcohol are its melting and boiling points.
The melting and boiling points of ethanol are about -114 و and 78., Respectively.
For comparison, the melting and boiling points of mercury are about -39 و and 7 357, respectively.
This means that mercury freezes faster than alcohol and ethanol turns into gas sooner than mercury.
So if you want to measure a very cold item, you have to use an alcohol thermometer.
But make sure the temperature is not lower than -114., Otherwise the frozen ethanol will expand and your thermometer will probably break.
Likewise, if you want to measure the temperature of a very hot item (but not warmer than 357.) You must use a mercury thermometer.
Mercury is harder and more expensive to find than alcohol, so if you need to measure the outside air temperature, you should use an alcohol thermometer.
But to measure the temperature of a hot object, such as the temperature of a car engine, you have to spend more and use a mercury thermometer.
There are a number of other important differences between mercury and alcohol. Mercury is highly toxic and alcohol is flammable.
Why is alcohol used in thermometers?
Alcohol can be used in some thermometers due to its very low freezing point.
It can also be used in cold spaces such as freezers.
However, it is not suitable in very hot weather conditions due to the low boiling point.
Why was the alcohol thermometer invented?
Because it was more accurate than the first thermometer, the same water thermometer invented by Galileo in 1542.
What kind of alcohol is used in thermometers?
Different types of alcohol are used for different purposes in thermometers, but ethanol is the most common.
What are the advantages and disadvantages of using alcohol in a thermometer?
Advantages: They are cheap and can be clearly seen when they are red.
Disadvantages: They wet the surface, have low surface tension and low density.
What are the advantages and disadvantages of using alcohol in a thermometer?
When you use an alcohol-based thermometer, you do not need to flip the thermometer to read the temperature again.
(Unlike the mercury thermometer, which is needed to read the temperature accurately, you have to flip the thermometer, flip and flip and flip) ..)
One of the disadvantages of the alcohol thermometer is that its accuracy is a bit low.
The biggest advantage of alcohol is that it is not as toxic as mercury so if the alcohol thermometer breaks you will not be poisoned.
Why is mercury and alcohol used in thermometers?
Mercury has a high boiling point and can measure high temperatures, and alcohol has a low freezing point and can measure very low temperatures.
Therefore, very high and very low temperatures are used for accurate measurements.