Why Candle Drinks Water?

 Overview 

Have you ever thought that many daily-using kinds of stuff can be used to do a science experiment? Like today, we will show you a fabulous experiment by using what you can easily get at home. Let’s have a look at it, now.

Age: 8+        Est. Time: < 30mins

 Safety 

1. Adult supervision.
2. There should be no flammable materials around in case of fire.
3. Wear protective gloves and goggles.

 Material list 

• Birthday candle
• Water
• Glass container
• Plate (or flat-bottom baking dish)
• Food coloring(optional)
• Lighter
• Bottle lid

 Instruction 

Step 1/2 - Dey the water with food coloring and pour the colored water in the plate.

Step 2/2 - Fix the birthday candle to a bottle lid, place it in the middle of the plate, light the candle, and cover it with the container. See what happens!

 Troubleshooting 

Why doesn't water rise in?
- It may be that the plate deforms and it is stuck to the glass container so close that there is no room for water to enter the bottle.
- If the candle fire is too small, the produced temperature inside the bottle will not change that much, and thus, the water will not rise in that much.

 Question to Ask 

1. Why does the water rise in the bottle?
2. Is it the same that the height of water rises in different containers?
3. Does the amount of candle affect the result?

 Scientific Description 

There are two rational behind the rise of water: First, the burning candle raises the air temperature in the container. According to Charles's law “the ideal gas state equation PV=nRT”, if the temperature rises, the gas volume increases and the volume of the container do not change, so some gas escapes from the container as you can see in the video that bubbles were coming out of the water. After the candle dies, the temperature of the air inside decreases so the pressure inside the container decreases, and the atmospheric pressure is stronger than the pressure inside the container so the water will enter in the container until the pressure inside the bottle is equal to the atmospheric pressure. Second, the burning of candle consumes oxygen to generate carbon dioxide and water. The volume of oxygen consumed is more than that of carbon dioxide produced. The amount of gas in the bottle is reduced so the pressure inside the bottle is reduced, which creates a vacuum and the water gets sucked in to take the place of the deduced air in the container.

 Extensions 

Use the different volumes of containers or different amounts of candles to attain different water levels and check out influence factors.

 Disposal 

Pour the liquid into the sink.  Do not forget to wash what you have used.