Explain why a rapid stream of bubbles comes out of the bell tube as the sample reaches its boiling point temperature?

Explain why liquid runs up the empty bell tube as the sample is cooled back down to its boiling point temperature?

What are you doing in this experiment?

When a sample reaches its boiling point temperature, the rapid stream of bubbles that come out of the bell tube is a result of the phenomenon known as boiling. Boiling occurs when the temperature of a liquid reaches a point where the vapor pressure of the liquid is equal to the atmospheric pressure surrounding it.

To understand why this happens, we need to consider the properties of liquids and gases. Liquids are made up of molecules that are closely packed together but still have some freedom of movement. These molecules are constantly in motion, colliding with each other at different speeds. Some of these molecules near the surface of the liquid gain enough energy from their surroundings to break free from the attractive forces and enter the gas phase.

As the sample is heated and its temperature rises, the average kinetic energy of the liquid molecules also increases. This leads to an increase in the number of molecules with enough energy to evaporate from the liquid and form a gas. These gas molecules escape the liquid and form bubbles, which then rise to the surface and escape into the surrounding atmosphere. The rapid stream of bubbles observed in the bell tube is a result of this process.

Conversely, when the sample is cooled back down to its boiling point temperature, the liquid runs up the empty bell tube. This phenomenon is called condensation. As the temperature decreases, the average kinetic energy of the gas molecules decreases as well. This reduction in energy causes the gas molecules to slow down and lose momentum. Eventually, the attractive forces between the gas molecules become strong enough to cause them to come closer together and form a liquid.

When the gas molecules condense, they lose their freedom of movement and adopt the more ordered and closely packed arrangement of a liquid. Along with this condensation, the gas volume decreases, and the pressure decreases as well. This decrease in pressure creates a partial vacuum in the bell tube, which draws the liquid up the tube.

In summary, the rapid stream of bubbles during boiling is caused by the increase in temperature, leading to the evaporation of liquid molecules. On the other hand, as the sample is cooled down, condensation occurs, causing the gas to turn back into a liquid and resulting in the liquid rising up the empty bell tube due to the decrease in pressure.