Question

Advantages and Disadvantages of mercury, alcohol and water as a thermometric liquid

Answer 1

Advantages of mercury as a thermometric liquid.
-It is a good conductor of heat and therefore the whole liquid reaches the temperature of the surroundings quickly.
-It does not wet (cling to the sides of) the tube.
-It has a high boiling point
-It expands uniformly (linear expansion) and responds quickly to temperature changes, hence is sensitive.
-It has a visible meniscus.
Disadvantages
-Mercury is very poisonous.
-its expansively is fairly low
-it is expensive
-It has a high freezing point therefore it cannot be used in places where the temperature gets very low.

Alcohol has a thermometric fluid
-Alcohol expands uniformly.
-It has a low freezing point (-115 degreecentigrade) therefore it is very suitable for place where the temperature gets very low.
-It has a large expansively
-It is an easily available cheap liquid, which is safe to use

Disadvantages of alcohol
-it wets the tube
-it has a low boiling point (cannot be used in places with high temperatures)
-it does not react quickly to changes in temperature
-It needs to be dyed, since it's colourless.

Disadvantages of water

-Water has high specific heat capacity. So it cannot be used for measuring small temperature differences.

- Water will wet the surface of the glass tube. It is a sticky substance.

- Water is transparent

Answer 2

Advantages of mercury as a thermometric liquid

• It is an opaque shiny  liquid which can be easily detectable through the glass of the thermometer.
• It has a wide temperature range between $-39$ to $35$ degree Celsius.
• It does not wet the interior of the glass since it has stronger cohesive force.

Disadvantages of mercury as a thermometric liquid

• It cannot be used in very cold temperature since it freezes below $-39$ degree Celsius.

Advantages of alcohol as a thermometric liquid

• it can be used to measure very low temperature as it's freezing point is below $-100$ degree Celsius.
• It has greater temperature coefficient of expansion compared to mercury.

Disadvantages of alcohol as a thermometric liquid

• Alcohol is a volatile liquid as it evaporates quickly.
• It is a transparent liquid, therefore taking readings will be tiresome.
• It rate of expansion of alcohol is not uniform.

Advantages of water as a thermometric liquid

• It is not corrosive to the container.
• It is the most cost effective thermometric liquid.

Disadvantages of water as a thermometric liquid

• It has a very low temperature range.
• It is transparent liquid hence very hard to take the readings.

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