Cool Science Gadget: Hand Boiler

During a Science lesson, one of my lovely pupils, Theresa, brought along a hand boiler. The class was excited. They found it cool.

Steps:

1. Hold the bottom bulb of the hand boiler in your hands and squeeze it.


2. Observe what happens.

Observation:

When you hold the bottom bulb of the hand boiler in your hands and squeeze it, you will see the liquid bubbling and it will go up to the top bulb.

Watch a video...

Challenge:

How do you get the liquid back to the bottom bulb of the boiler without turning it over?

Solution:

Hold the top bulb in your hands Or

Wait for the air in the bottom bulb to cool off

How does the hand boiler work?

Teacher Serena's Explanation:

The liquid in the hand boiler has a low boiling point. When we hold the bottom bulb in our hands, heat from our hands is transferred to the bulb and to the liquid and vapour above it. The vapour that sits above the liquid gains heat and expands. This additional warmth causes more liquid to evaporate.

This Science toy demonstrates the relationship between temperature and pressure. The hand boiler is a closed container. Therefore, as temperature goes up, the molecules of gas in the container move faster and this causes pressure to increase. As the pressure increases in the lower bulb, the liquid will be pushed up the tube into the top bulb. When the level of the liquid in the bottom tube falls below the end of the tube, vapour can travel up the tube and rise through the liquid, giving the appearance of boiling.

Conversely, as the air in one of the chambers cools off, the molecules of gas slow down, lowering the pressure. The liquid will move from an area of high pressure to an area of lower pressure.

~ Serena's Greenhouse