Question

The chemical used for cooling in refrigeration is:
A. ${\text{C}}{{\text{O}}_2}$
B. ${\text{N}}{{\text{H}}_{\text{4}}}{\text{OH}}$
C. ${\text{N}}{{\text{H}}_{\text{4}}}{\text{Cl}}$
D. Liq. ${\text{N}}{{\text{H}}_3}$

Answer 1

Hint: The chemical used in refrigeration must have a good vaporization property i.e. it should vaporize easily at to produce the desired temperature.

Complete step by step answer:
Carbon dioxide cannot be used for cooling in refrigeration because it has high working pressure.
Ammonia can vaporize easily at the desired temperature.
When ammonia is evaporated its pressure is very low.
Thus, ammonia is used for cooling in refrigeration.

So, the correct answer is “Option D”.

Additional Information:
The other chemicals used for cooling are freons. Freons are also known as chlorofluorocarbons. Freons are stable, inert and non-flammable gases and have a very low boiling point. Freons evaporate easily to keep the temperatures low. Also, freons are non-corrosive.
Freons are also used in air conditioners.
Freons have many adverse effects on humans as follows:
1. Breathing problems
2. Fluid build-up in lungs
3. Nausea and vomiting
4. Cough
5. Dizziness
6. Burning of skin

Note:
Other reasons to use ammonia in refrigeration are:
1. Ammonia can condense at very low pressures.
2. Ammonia does not corrode metals such as steel used in the refrigerators.
3. The pungent smell of ammonia makes it easily detectable and thus, leakages can be easily detected.
4. Ammonia has high heat of vaporization and absorbs large amounts of heat and reduces the temperature of the surrounding.