Hello everyone,

This is my first participation in #creative-sunday and I hope you like this experiment I did a few days ago with my 8 year old cousin Natalia.

Origin of the experiment

Two weeks ago, my cousin and her parents came to spend a few days of their holidays at my house, and that's why I gave her this set of experiments.

In fact, it is a very complete set with several reagents such as sodium bicarbonate, citric acid, various dyes, beakers, plastic pipette, rod.

The rise of water when the candle is extinguished

Materials needed

A deep dish
A beaker
A candle
A lighter
Water
Colouring
Stick

Method

Step 1:

In a deep bowl of water, add a few drops of one of the dyes provided in the science kit.

Step 2:

Using the stick from the kit, my cousin stirred the dye well so that it mixed well with the water.

I recommend doing this experiment with the dye because it is more colourful.
Alternatively, you could use some food colouring or a few drops of paint.

Step 3:

Place the candle on the plate so that it floats in the glass. To do this, adjust the amount of water.

Step 4:

Using a lighter or a match, light the candle floating in the water.

At this point, although we cannot see it, a combustion reaction is taking place, releasing CO₂, and there is a high temperature in the gases near the candle.

Step 5:

We put the glass on the candle.

At this point what happens is that the CO2 from the combustion, which is at a higher temperature, displaces the air and therefore the O2 to the lower part of the glass and this O2 in turn is consumed by the candle in its entirety and causes the candle to go out.

So the first lesson of this experiment is that the best way to extinguish a fire is to isolate the fire from the oxygen.

This lesson is very useful in the kitchen, because if our oil is burning in the frying pan, the best way to extinguish it is to put a lid on the pan to stop the fire from getting oxygen.

Step 6:

When the candle is extinguished, the phenomenon of the water level inside the glass begins to rise gradually or rapidly, depending on several physical factors such as the atmospheric pressure at that moment, the temperature of the water, etc.

As you can see in the video, in our case the rise was quite abrupt and sudden.

Source

Explanation

The explanation of what happens in this part of the experiment is quite complex.

When the candle is extinguished, there is a gradual cooling of the gases inside the glass. As a result, the gases inside the glass lose speed, causing a loss of pressure, to the point where the pressure on the outside of the glass, i.e. atmospheric pressure, causes the water inside the glass to be pushed.

We repeated this experiment 3 times in the same afternoon because my cousin loved watching the water go up the glass and I think it is a good science experiment for a fun Sunday afternoon.

Kind regards.