Boiling Water Under Reduced Pressure

The video tutorial demonstrates an experiment where a beaker of water is placed under a bell jar and the surrounding air pressure is lowered using a vacuum pump. As the pressure decreases, the water begins to boil due to its vapor pressure exceeding the surrounding pressure. This boiling causes the water to lose heat and eventually freeze, even while boiling. When the pressure is returned to normal, the water remains frozen, illustrating the effects of pressure on boiling and freezing points.

What is the purpose of using a liquid nitrogen cold trap in the experiment?

• To cool the water

• To heat the bell jar

• To prevent water from entering the pump

• To increase the pressure

Which equipment is used to lower the surrounding air pressure in the experiment?

• A thermometer

• A vacuum pump

• A heater

• A barometer

Why does the water begin to boil when the pressure is reduced?

• The water is heated

• The vapor pressure of the water exceeds the surrounding pressure

• The bell jar is removed

• The water is cooled

What happens to the water's temperature as it boils under reduced pressure?

• It decreases

• It remains constant

• It increases

• It fluctuates

What is observed when the pressure continues to drop while the water is boiling?

• The water turns into steam

• The water evaporates completely

• The water remains liquid

• The water freezes

What is the state of the water when the bell jar is returned to atmospheric pressure?

• It remains frozen

• It is gaseous

• It evaporates

• It is liquid