Question

A bottle of liquor ammonia should be cooled before opening. Explain.

Answer 1

The answer to this question is based on the concept of vapour pressure of ammonia at the room temperature and the fact that explains this gives you the required answer.

Complete answer:
In the lower classes of chemistry, we have come across the concepts of colligative property of the solution that also involves the facts about vapour pressure.
Now, let us see what vapour pressure is and how it varies with various liquids and the effect of temperature on it.
- Vapour pressure is the measure of tendency of a material to change into the gaseous or vapour state and this increase with temperature.
- Based on this definition of vapour pressure we can say that when the vapour pressure at the surface of a liquid becomes equal to the pressure that is exerted by surroundings is called boiling point of that liquid.
- In case of ammonia, at room temperature, the vapour pressure of this liquid that is liquor ammonia is very high and therefore because of this fact, the liquid ammonia will evaporate at this temperature.
Thus, cooling of ammonia is required which decreases the vapour pressure of this liquid and hence the liquid remains in the same state and therefore the bottle of liquor ammonia should be cooled before opening.

Note:
Note that the meaning of liquor ammonia is nothing but it is the concentrated solution of ammonia which is also called as aqueous ammonia whereas liquid ammonia is the ammonia gas which is liquefied under pressure.