candle water bottle experiment

Getting the facts right

Photos of the experiment

An exhibit of explanations

What do we learn, appendix: the chemical equation for general n.

Appendix: the ideal gas equation

Added March 20, 2011

Added September 26, 2011

Added November 20, 2011

Added January 23, 2012

Added February 5, 2013

Added January 21, 2014

Added March 30, 2021

Added January 28, 2024

Why Does the Water Rise?

A candle and some rising colored water reveal a hidden property of air that’s around you all the time.

Print this Experiment

Watch closely and use everything you know about air pressure differences to explain the mystery of the rising water. Look for clues that explain why the water rises into the container. It may not be what you think it is so keep your eyes open as you collect data. The best part is that you’ll likely have to do the experiment several times to confirm how air pressure is involved.

Experiment Videos

Here's What You'll Need

Plate or shallow dish, clear, slender container, 1 cup (237 ml) of room temperature water, food coloring, adult supervision, let's try it.

Add 2-3 drops of food coloring to the water. This will make the movement of the water easier to see later. It’s interesting to watch how the drops of coloring spread through the water before stirring it.

Pour the colored water into the plate. You want about a half-inch (1 cm) deep puddle in the plate. More is OK.

Set the candle straight up in the puddle in the center of the plate. To make sure everything will fit, place the slender container over the candle and into the water. Make sure its base is well above the candle wick and its top edge is submerged under the water. Add water if needed. When you’re happy with the setup, remove the container.

When the candle is stable, the water is calm, and an adult is present, light the candle. The candle flame needs to burn brightly.

There’s no need to rush this Step; there’s a lot to watch anyway. Turn the container over again and lower it over the burning candle. Place the container on the plate in the water and let go but don’t take your eyes off of the water level inside it. You may see bubbles coming from inside the container. At first, the candle stays burning and the water level rises slowly. About the time the candle goes out, the water rises quickly. This is the mystery: why does it rise?

Repeat the procedure several times so that you can write or draw an explanation as to why the water rises. HINT: The difference in air pressure inside and outside the container is important.

How Does It Work

A common misconception is that the consumption of oxygen by the flame in the container is a factor in the water rising. There may be a slight possibility that there would be a tiny rise in the water from the flame using up oxygen but it’s extremely small compared to the actual reason. Simply put, the water would rise imperceptibly at a steady rate as the oxygen were consumed. You likely saw the level rise almost all at once and pretty much after the flame went out.

At first, the flame heats the air inside the container and this hot air expands quickly. Some of the expanding air escapes from under the vase where you might have seen some bubbles. When the flame fades and goes out, the air in the container cools and cooler air contracts or takes up less space. That contraction creates a weak vacuum – or lower pressure – in the container. Where’s the higher pressure? Right! It’s outside the container pressing down on the water in the dish. The outside air pushes water into the container until the pressure is equalized inside and outside the container. The water stops rising when that pressure equalization is reached.

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Posted on Last updated: December 8, 2021 By: Author Kim

Categories STEM Activities

Rising Water Experiment – Magic Water Science Experiment

Rising Water Experiment: a magic rising water science experiment.

• Ages: Preschool , PreK , Kindergarten, Elementary
• Difficulty: Easy
• Learning: STEM , Air Pressure, Ideal Gas Law, Charles’s Law

Did you know you can make water rise without touching it?

Nope, it isn’t magic. It’s science. Surprisingly simple science in fact. This science experiment comes together in minutes, but it will captivate your children.

Here is how to do the raising water experiment, simple glass and candle STEM magic.

What's In This Post?

Supplies for your Glass and Candle Experiment

How to do the rising water experiment, the science, the chemical component, the physical component, the big picture, what should children take away from this science experiment, conservation of matter, charles’s law, ideal gas law, ask a question, magic water science experiment, free printable raising water experiment instructions, instructions, rising water experiment.

This experiment uses at-home materials and is fascinating! It does require adult help, but adults will love it too.

You only need a few items to make this magic water STEM experiment work. Here is what you need to gather up:

• Glass or Jar
• Small Votive Candle
• Shallow Dish
• Food Coloring (Optional)
• Matches or Lighter

Before we even get started please remember that an adult needs to be present for this experiment. We are using fire, which can be dangerous, so be smart.

Step 1: Take a sallow dish and fill it with water. You want just enough to cover the bottom.

Step 2: If you want, add food coloring to the water. This just makes it easier to see and is fun, so totally optional.

Step 3: Place your small votive in the middle of the dish.

Step 4: Light the candle, then quickly place the empty glass over the flame, touching the water. Now wait while the candle burns out.

Step 5: Watch as the water rises up into the glass!

The number one safety tip here is to be careful with the flame! This experiment must be done with adult supervision at the bare minimum. With younger children, like preschoolers, this needs to be an adult-led experiment.

This STEM activity also uses glass, so it is a good idea to be careful in case it falls or breaks.

Clean-up for this activity is pretty simple. Slowly lift the bottle off of the candle.

Once the bottle is off, gently blow the candle out. Let the candle cool (or have an adult get it), remove it from the dish, and dump the water down the drain. That’s it!

More must do activities!

How the Rising Water Experiment Works

This is a pretty cool experiment, but it is important to talk about what actually makes this happen. It’s fun to say it is magic, but as my kids tell me, ‘It’s better. It’s science.’

There are two main components of this experiment that cause the water to rise, a physical component and a chemical component. These two components work together to make this experiment happen.

The candle burning creates a chemical reaction. The flame burns both the paraffin (candle wax) and the oxygen under the glass. This reaction uses up oxygen and creates water and carbon dioxide as a result. Twice as much oxygen is burned than carbon dioxide produced, so the volume of air in the glass decreases.

(Note the total amount of matter in the jar remains the same. Conservation of matter tells us this. But some molecules are larger than others and take up more space in terms of volume.)

The physical component is why the water level in the glass doesn’t rise as soon as the candle is covered. The candle warms the air, and this increases the air volume inside the glass.

When the candle burns out (because all the oxygen is used up), the temperature cools quickly. This temperature decrease means the volume also decreases, which lets the water rise to fill up that space. This is called Charles’s Law.

Charles’s Law tells us that the ratio of volume to temperature must remain the same, so if one goes down the other goes down too.

These two parts of the experiment work together. Both the volume change and temperature also affect the pressure in the system we created. When temperature decreases (the physical component) and the size of the matter decreases (the chemical component), the pressure of the gas inside the glass decreases too.

This lower pressure inside means the water can rise as well. This is explained by the Ideal Gas Law.

The idea of air pressure can be a bit challenging for young children to understand. It isn’t something they can clearly see, so that makes sense. But they can understand something changing size, in other words when volume changes.

If the air inside the glass takes up less space, it makes sense for the water to fill in that space and rise inside the glass.

I understand that we went over a lot of more complicated concepts here. (And don’t worry, I’ve listed the definitions for the terms below to help out.) Am I really expecting young kids to understand and retain all this?

No. I mean, it would be cool if they did. And some might. But realistically that is not the point of this kind of science. The purpose of giving these explanations is so that you as a caregiver can quickly get the reasoning behind this project and interpret it for your children.

It is helpful for your children to see these experiments. Even if they don’t fully understand the details, this experience is adding to their understanding of how the world around them works. It builds their science base.

Using the vocabulary helps kids as well. First, it gives new words which are always helpful for communication skills. But I think, more importantly, it demystifies science later in life. Science can feel like a whole new language as we get older, and that can be very intimidating. If we have been exposed to these terms though, it’s less scary. We might not know exactly what they mean but we know that we have heard them before. This helps kids feel like science belongs to them. Because it does.

Helpful Definitions

Here are a few helpful definitions for the raising water experiment.

The conservation of matter law states that matter is not destroyed or created. It can change forms, but the total amount stays the same.

Charles’s Law tells us that the volume of a gas is directly proportional to the temperature of the gas. As the volume decreases, the temperature decreases, for example.

The Ideal Gas Law describes the conditions a gas is under and how those conditions will vary as compared to each other. The pressure of the gas multiplied by the volume will always equal the number of moles multiplied by the temperature and ideal gas law constant.

The Scientific Method

Since an adult is needed to run do this experiment with kids (fire safety!), it is a great time to talk through the scientific method! Here is a guideline of what that can look like with this STEM experiment.

(And don’t forget to learn all the life lessons that come along with the scientific method here: Beyond the Science- What Kids Are Really Learning .)

Ask your child, what do they think is going to happen when we put the glass on the candle? The key here is to listen and let them think it through. No answer is too far out there or wrong at this step.

The observation step is key throughout any experiment, but take a moment and look at their components. What do they notice about them? How do they normally behave? What do they already know about them?

Narrow down your potential answers and decide on one or a couple of outcomes you think are most likely. This is your hypothesis.

Time to run the experiment! Encourage your children to keep watching what is happening. (In this particular observation, sight is going to be the key thing to focus on. Some touch is possible, watching out for the flame of course. And you can encourage smell and hearing for practice.

What did they observe? Now is the time for them to tell you everything they can about what just happened.

This is where we form the conclusions and apply the information we learned. Do they think this will always happen? How did the results match or differ from their hypothesis?

Real experiments always lead to more questions. What does your child want to try next? What would they change in the experiment? Does more water in the dish change anything? Can they try to suck up all the water? Would adding a different liquid change the results?

Even if you aren’t able to complete any of their additional experiment ideas, it is a good idea to think of ways to explore more. Plus it is amazingly fun to hear all the ideas kids have.

This is a great experiment to do over and over. It’s fast, cheap and full of fun learning. It’s a must-do!

Let’s find your next fun activity!

Raising Water Experiment

How to do the raising water experiment that will wow kids!

• Food Coloring (optional)
• Lighter or Matches
• Fill your shallow dish with enough water to cover the bottom. Add food coloring. (optional)
• Place your votive in the middle of the dish.
• Light the votive candle.
• Place the glass upside down over the candle.
• Wait for the candle to burn out and watch the water rise!

This is a science experiment that needs adult supervision and help. It uses fire and needs an adult to be safe.

To clean up, gently pull the glass off the candle. Make sure the candle cools and the water can go down the drain.

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Candle and Water Trick

As the temperature falls, so does the pressure

◊ Food colour

1. Put a very little water on a plate, and mix in a couple of drops of food colour.

2. Place a candle in the middle of the plate, and light it. Slowly bring a glass down on top of the candle until it is standing in the water, on the plate.

3. Watch what happens next!

The burning candle heats the air above it, including the air that goes into the glass. Once the glass is standing on the plate, the burning candle uses up all the available oxygen in the glass, then goes out. As it does so, the air in the glass cools, and as it cools, the air pressure in the glass falls below atmospheric pressure. Water is drawn into the glass until the pressure is equalised. You can turn this experiment into a competition by placing a small coin on the plate under the water and, offering students a variety of possible tools, seeing who can retrieve the coin without getting their fingers wet.

So how does this relate to atmosphere?

When we measure the air pressure at the surface of the Earth, we are literally measuring how much air is above us. If the air pressure falls, there is less air above us, if the air pressure rises, there is more air above us. The relationship between temperature and pressure is very important – as the temperature falls, so does the pressure and as the temperature rises, so does the pressure. That means that as air moves up in the atmosphere and the pressure falls (because there is less remaining atmosphere above) its temperature has to fall as well. Typically, the temperature of the atmosphere falls about 6°C for each 1000m you go up –so the tops of mountains are always much colder than the valleys below. This experiment also demonstrates how storm surges work – when the air pressure is low over a sea or ocean, the water level can rise. This can have devastating consequences – for example the North Sea flood of 1953.

Another experiment

For another experiment looking at the relationship between temperature and pressure, all you need is a plastic syringe (the sort sold in pharmacies for administering medicine to babies). With your finger over the nozzle, pour a little very hot, but not boiling, water into the syringe. There will be a bubble of air at the bottom, so you won’t scald your finger! Now use the plunger to push all but 3ml of the water out, then put your finger over the nozzle again, and pull the plunger out. As the pressure in the syringe falls, the temperature falls but so does the boiling point of water – you should see the water starting to boil!

More experiments and demonstrations

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NOTIFICATIONS

The great candle experiment.

• + Create new collection

In this activity, students cover a lit candle with an inverted jar in a saucer of water. The flame expires and the water rises up in the jar.

By the end of this activity, students should be able to:

• engage in scientific debate, using observation to present ideas
• understand the effects of heat in terms of expansion and contraction in this experiment.

Download the Word file (see link below) for:

• introduction/background notes
• what you need
• discussion questions
• scientific explanation
• student instructions.

Nature of science

Explanations of observations can be tricky. Scientists need to be careful that their prior knowledge doesn’t lead to plausible explanations that actually turn out to be incorrect – or not the whole reason why something might happen.

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Rising Water Experiment

Light a fire under middle school science and heat it up! Place a burning candle in the water and watch what happens to the water. Explore how heat affects air pressure for an awesome middle school science experiment. This candle and rising water experiment is a great way to get the kiddos thinking about what is happening. We love  simple science experiment s; this one is super fun and easy!

Candle in Water

This candle experiment is a great way to excite your kiddos about science! Who doesn’t love watching a candle? Remember, adult supervision is required, though! We love  simple science experiment s; this one is super fun and easy!

This science experiment asks a few questions:

• How is the candle flame affected by placing a jar over the candle?
• What happens to the air pressure inside the jar when the candle goes out?

💡 Make sure to check out all our chemistry experiments and physics experiments !

Click here to get your free printable STEM activities pack!

Candle in a Jar Experiment

You need to change one variable if you want to extend this science experiment or use the  scientific method  for a science fair project .

EXTEND THE LEARNING: You could repeat the experiment with candles or jars of different sizes and observe the changes.

💡Learn more about the scientific method for kids here .

• Middle School Science
• Elementary Grades Science
• Tea light candle
• Bowl of water
• Food coloring (optional)

Instructions:

STEP 1: Put about a half inch of water into a bowl or tray. Add food coloring to your water if you like.

STEP 2: Set a tea candle in the water and light it.

ADULT IS SUPERVISION REQUIRED!

STEP 3: Cover the candle with a glass, setting it in the bowl of water.

Now watch what happens! Do you notice what happens to the level of water under the jar?

Why Does the Water Rise?

Did you notice what happened to the candle and the water level? What’s happening?

The burning candle raises the air temperature under the jar, and it expands. The candle flame uses up all of the oxygen in the glass, and the candle goes out.

The air cools because the candle has gone out. This creates a vacuum that sucks up the water from the outside of the glass.

It then raises the candle up on the water that enters the inside of the glass.

What happens when you remove the jar or glass? Did you hear a pop or popping sound? You most likely listened to this because the air pressure created a vacuum seal, and by lifting the jar, you broke the seal, resulting in the pop!

More Fun Science Experiments

Why not also try one of these easy science experiments below?

Printable Science Projects For Kids

If you’re looking to grab all of our printable science projects in one convenient place plus exclusive worksheets and bonuses like a STEAM Project pack, our Science Project Pack is what you need! Over 300+ Pages!

• 90+ classic science activities  with journal pages, supply lists, set up and process, and science information.  NEW! Activity-specific observation pages!
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Science in School

A twist on the candle mystery teach article.

Author(s): Steven Ka Kit Yu

Three candles of different heights are lit in a closed space. Surprisingly, the longest candle goes out first. Can you solve the mystery?

In a classic demonstration of the candle mystery, three lit candles of different heights are covered with a gas jar (see figure 1) and the tallest candle goes out first. This happens because carbon dioxide produced from burning has a higher temperature, so it rises and accumulates at the top of the jar. Then the carbon dioxide gas cools down, falls, and extinguishes the tallest candle first. This article builds on the classic demonstration of the candle mystery and advances it in three ways. Firstly, the 5E instructional model [ 1 ] is used to develop learning activities that require students to construct, revise, and apply scientific explanations in unpredictable contexts. Secondly, these activities aim to help students test their hypotheses by using and coordinating multiple pieces of evidence. Thirdly, these activities include experiments and discussion tasks to challenge students to predict and explain results. By adding variables to the candle mystery, you can engage students and promote critical thinking and scientific understanding.

The experiments can be conducted as demonstrations or as hands-on practical work for small groups of students. They are quick and easy. The activities can be used with students aged 11 to 16.

Safety notes

• Follow all fire safety regulations and have fire extinguishing materials on hand.
• Wear safety goggles throughout the experiments. If students are performing any steps themselves, they should do the same and be warned to take care around open flames.
• The gas jar can become very hot during and immediately after candles are extinguished. Students should be warned not to touch it with bare hands and care should be taken (e.g., wear heat-resistant gloves when lifting the hot gas jar and/or lift the gas jar when it has cooled to room temperature).
• Make sure all candles are extinguished after each experiment.
• Ensure sufficient ventilation, for example, by opening windows.

Activity 1: Engaging and exploring student ideas for the candle mystery

This activity aims to set up a scenario to engage students in inquiry. When three candles of different heights are lit and covered with a gas jar, students are prompted to predict and explain which candle they think will go out first. Allow 40 minutes for the prediction discussion, experiments, and collaboration.

• Large gas jar (large enough to cover three candles)
• Three candles of different heights
• Heat-proof mat
• Hot-air gun, 240 V, 2000 W (optional: used to heat the blade to cut candles to different heights)

Worksheet 1

Preparation

Before the lesson, the setup should be prepared by the teacher or teaching assistant.

• Cut three candles to different lengths with a hot blade preheated by a hot-air gun (see figure 2).

• Align the three candles on a heat-proof mat, close enough that they can be covered with the gas jar.
• Cover the three candles with the gas jar (without lighting them, figure 3).

Practical tips :

• To ensure fair testing and expected results, ensure that the wicks are identical in length, and that the heights of the candles differ significantly.
• Perform a test run before the lesson to check that the setup works and to get a sense of how long it takes for the first candle to go out.
• Show the setup to students and encourage them to think about what would happen if we lit the candles (and replaced the gas jar). Ask them which candle they expect to go out first.
• Have them write down their own ideas first (and record them in worksheet 1) and then optionally have them discuss this in groups and then with the class. Ask them which candle they expect to go out first.
• Remove the jar, light the candles, and watch what happens. Depending on the setup (e.g., candle length, jar size), the candles should go out within a few minutes. Students often find the result (the tallest candle goes out first) mind-blowing.

• Optional: have students repeat the experiment (or watch a recording) and record the times required for each candle to go out. Combine the results and draw a graph.
• Discuss the results and encourage students to reflect on their initial predictions. Were students surprised by the results? Did the results match their predictions? Does it make them think differently about their explanation?
• A more in-depth discussion about why the tallest candle goes out first follows in Activity 2. If Activity 2 is not being used, part 1 (Why does the tallest candle go out first?) of Activity 2 can be carried out here.

Watch a demonstration of Activity 1.

You can adopt the think–pair–share approach to engage with student thinking in step 1. In this approach, students are asked to predict and explain individually which candle would go out first. They then share their predictions and explanations in groups of three or four, followed by a whole-class discussion. You can capture students’ initial ideas and reasoning and stimulate students’ thinking using the following questions:

• Why do you think the tallest or shortest candle goes out first, or why do you think the candles go out at similar times?
• After listening to your classmates’ ideas, would you change your prediction?
• How would you convince others that your prediction is correct?

Activity 2: Explaining the candle mystery

Instead of explaining to students that hot carbon dioxide rises to the top of the jar and extinguishes the tallest candle first, a discussion to help them think it through themselves will lead to better understanding. It is important to allocate time and support for students to reflect thoughtfully. They can test the explanation by monitoring changes in carbon dioxide concentration [ 2 ] and the temperature inside the gas jar. The activity takes about 40 minutes.

• Three plastic bottle caps
• Adhesive putty like Blu Tack or some adhesive tape
• Bicarbonate indicator solution (10 ml)
• Three temperature sensors (e.g., PASPORT chemistry sensor)

Evidence cards

Worksheet 2

• Timer (optional)

Part 1: Why does the tallest candle go out first?

• Ask students why they think the tallest candle goes out first. If they mention CO 2 , you can prompt them to think about how to test their hypotheses.
• Why did the candles go out before they burned down?
• How does the air in the jar change as the candle burns?
• What chemical process creates flames? What are the outputs of combustion?
• What happens to gases when they’re heated?

You can also link this to the real-life situation of escaping from fires by asking questions like:

• What are the essential actions to be followed in case of a fire inside a building?
• Why do we stay low to crawl through smoke-filled rooms or corridors?
• You can use the evidence cards (figure 4) to help guide the discussion.
• Once they have some ideas involving CO 2 build-up and temperature differences, ask how they would test their hypotheses. Encourage them to think about what variables would need to be kept the same to ensure a fair test.
• The experiments in parts 2 and 3 can be used to investigate some of these variables, or you can come up with your own.

Part 2: Monitor the carbon dioxide concentration

Safety note

A safe distance between the flame and Blu Tack/tape should be maintained to avoid melting of the Blu Tack/tape.

• Set up the experiment as for Activity 1. You can use the same candles but ensure the wicks are the same lengths.
• Fill three plastic bottle caps with bicarbonate indicator and use Blu Tack or tape to stick them at different levels inside the gas jar (figure 5).
• Repeat the procedure detailed in Activity 1, and observe colour changes to the bicarbonate indicators at the end of the experiment (figure 6).

Practical tip

To ensure fair testing, the amounts of bicarbonate indicator added to the bottle caps need to be the same.

Watch a demonstration of Activity 2a.

Part 3: Monitor the change of temperature

• Calibrate the temperature sensors if necessary.
• Set up the experiment as for Activity 1. You can use the same candles but ensure the wicks are the same lengths and the glass jar is replaced to ensure the experiment starts at room temperature.
• Connect three temperature sensors and use Blu Tack or tape to stick the sensors at different levels inside the gas jar (figure 7).
• Repeat the procedure detailed in Activity 1, and collect data for temperature changes at different levels inside the gas jar (figure 8).

The results should show that the carbon dioxide levels and temperature rise more towards the top of the jar. Discuss with students whether these results support their explanations. Are there any alternative explanations that are consistent with the results?

Activity 3: Elaborating and evaluating student learning about the candle mystery

To assess students’ deep understanding and ability to apply their explanations, you can introduce variations of the candle experiment in different contexts. Challenge your students to consider what they think might happen if we place the candles in separate jars. [ 3 ] Additionally, ask them to explore the results if we introduce an electric fan into the setup. This can be combined with another think–pair–share activity to promote discussion and evaluate their understanding of the concepts. Allow 40 minutes for the experiments and discussion.

• Portable fan

Worksheet 3

• Activity 3 explanation

Part 1: Burning candles in individual beakers

• Ask the students what they think would happen if the candles were lit in individual jars. This can be done using the think–pair–share approach.
• Secure three candles of different heights to the bench (this also works with two candles).
• Light the candles and cover each with a separate beaker (figure 9).
• Record the time required for each candle to go out.
• Repeat the experiment to get more reliable data.

To ensure fair testing, the volume inside the beaker must remain the same throughout the experiment. If a candle needs to be cut, the cut pieces should be placed inside the beaker.

Watch a demonstration of Activity 3a.

Part 2: Burning candles near a small fan

• Ask the students what they think would happen if a fan were placed in the jar. Place a portable fan near the three candles used in Activities 1 and 2, and turn the fan on.
• Repeat the procedure detailed in Activity 1, and record the time that the candle goes out.
• Repeat the experiment with the fan turned off.
• Compare the time taken for the candle to go out when the fan is on and off.

Practical tips

• To ensure fair testing, the volume inside the beaker must remain the same throughout the experiment. The electric fan should be placed inside the beaker, whether it is turned on or off.
• To repeat the experiment, you may fan the gas jar to restore it to room temperature and avoid the build-up of CO 2 , or you can use a new gas jar.

Watch a demonstration of Activity 3b.

The candles go out at similar times in the experimental setups with separate beakers or with an additional electric fan. The results contrast the experimental results in Activities 1 and 2. To ensure reliability of the results, students are encouraged to repeat their experiments, which can be performed within 5 minutes. Encourage students to provide explanations for their observations. Students are asked to construct explanations of how and why things happen in the setup using their explanations developed in Activity 2. You may give groups the model answer ( Activity 3 explanation ) at the end to compare it to their descriptions.

The activities based on simple twists to the classic candle experiment can serve to improve students’ abilities to develop, revise, and apply scientific explanations, as well as to explore scientific skills such as control of variables, hypothesis testing, and coordinating multiple pieces of evidence. As an extension activity, you could encourage students to handle quantitative data in an in-depth discussion and demonstrate their learning through report writing and group presentation. The process of predicting and explaining different unfamiliar contexts can help create valuable teachable moments that motivate students to learn.

[1] Bybee RW (2015) The BSCS 5E Instructional Model: Creating Teachable Moments . National Science Teachers Association Press. ISBN-10: 194131600X

[2] Cheng MW (2006) Learning from students’ performance in chemistry-related questions. In Yung BHW (ed.) Learning from TIMSS: Implications for Teaching and Learning Science at the Junior Secondary Level pp 51–74. Education and Manpower Bureau.

[3] Details for how to investigate candle burning: https://edu.rsc.org/resources/candle-burning-investigation-planning-an-experiment/619.article

• Watch demonstration videos of the experiments in Activities 1 ( candle mystery ), 2 ( CO 2 concentration ), and 3 ( individual beakers and electric fan ).
• Learn how to make convection currents visible using mist: Lim ZH, Shu A, Ng YH (2023) A misty way to see convection currents . Science in School 64 .
• Explore the nature of science by investigating a mystery box without peeking inside: Kranjc Horvat A et al. (2022) The mystery box challenge: explore the nature of science . Science in School 59 .
• Try some experiments with gases to illustrate stoichiometric reactions and combustion: Paternotte I, Wilock P (2022) Playing with fire: stoichiometric reactions and gas combustion . Science in School 59 .
• Learn about data visualization by sketching graphs from ‘story’ videos of everyday events: Reuterswärd E (2022) Graphing stories . Science in School 58 .
• Read about the environmental costs of fireworks: Le Guillou I (2021) The dark side of fireworks . Science in School 55 .

Steven Ka Kit Yu has been working in the education sector in teaching, research, and administrative roles. He was a secondary science teacher and a part-time lecturer in the Faculty of Education, the University of Hong Kong.

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Burning Candle, Rising Water Experiment

Introduction: Burning Candle, Rising Water Experiment

I saw a short video of this experiment on Reddit and thought it would be an interesting science experiment to try with the kids.

Here is our recreation of the experiment:

Step 1: Materials

Below is a list of the materials you will need for the experiment.

• Tall Glass with a slightly larger diameter than the candle
• Food Coloring or Mio
• Spoon (Optional)

Step 2: Add Food Coloring to Water

You can do the experiment with just water but colored water is easier to see. We used Mio instead of food coloring.

Step 3: Add Colored Water to Plate

You should experiment with different levels of water. We used about 1/4".

Step 4: Place Candle in Center of Plate

Candle should be placed vertical as shown.

Step 5: Light Candle

Light the candle. Note that a larger flame gives a more dramatic effect.

Step 6: Place Glass on Candle

Carefully place the glass container over the candle.

Step 7: Watch the Science in Action

I tried to grab some frames of the process. Notice how the colored water moves from the plate into the glass container. Once the candle flame goes out, you will see an inrush of water.

If you search for this on the web, you will see multiple ideas on how it works.

I took the explanation of Oliver Knill from the Harvard Math Department. He states in general terms: "The candle heats the air and expands it. This cancels the depletion of the oxygen temporarily and the water level stays down. When the oxygen is depleted, the candle goes out and the air cools. The volume of the air decreases and the water rises. The temporary temperature change delays the rise of the water"

For debate on the subject, see the following link:

math.harvard.edu

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Science at Home for Kids

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The Magical Candle

Today, we have a mind-blowing experiment! You will watch as water is magically pulled into an upside-down cup. However, you may need to ask your parents to help you during this experiment because it involves fire. Let’s get started!

What you need:

• A lighter or match
• A glass cup

• Place the candles upright in your tray.

• Pour the water into the tray.

• Ask your parents to help you light the candles.

• Place the glass cup over the candles and watch as the water in the cup rises.

How does this experiment work?

As we lower the cup over the candle, the candle heats the air inside the cup. The hot air starts quickly expanding in all directions, and some air travels out of the opening of the glass. Once all of the oxygen is gone, the flame goes out. Since there is no longer a candle heating the air, the air cools and contracts. This cool and contracting air creates a lower pressure vacuum inside the cup. Since gases exert a push from an area of high pressure into an area of low pressure, water is pulled into the cup until the air pressure inside the cup is equal to the air pressure outside the cup.

Source: “Rising Water Secret.” Steve Spangler Science , 17 Sept. 2015, www.stevespanglerscience.com/114wsks58tzofz7z9/.

So neat, and almost in time for my birthday! 🙂

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Why does the water rise?

It's a very popular experiment ( eg ), from elementary school : put a burning candle on a dish filled with water, cover the candle with an inverted glass: after a little while, the candle flame goes out and the water level inside the glass rises.

The standard explanation (as I recall it) was that combustion "burns" oxygen, and the consummed volume accounts for the extra water that goes inside the glass. Is this correct? I remember feeling (years later) uncomfortable with the explanation, because "to burn" is certainly not "to dissapear": I thought that oxygen combustion produces (mainly) $CO_2$ and hence one oxygen molecule would produce another $CO_2$ molecule, and the volume would remain basically the same. Perhaps $CO_2$ dissolves into the water? I would doubt that.

To add to my confusion, others state that the main cause is not the oxygen combustion but the changes of air temperature, that decreases when the flame goes out and makes the air inside the glass contract... which would rather invalidate the experiment as it was (and is) traditionally taught to students.

What is the right explanation?

(image from here )

Update : As from webpage linked in accepted answer, there are several effects here, but it's fair to say that the "traditional" explanation (consumption of oxygen) is wrong. Oxygen (plus paraffin) turn into $CO_2$ (plus water) (a representative reaction: $C_{25}H_{52}+38O_2 \to 25CO_2+26H_2O$ ). This would account for a small reduction in volume ( $25/38 \approx 2/3$ ), even assuming that this is the complete chemical picture (it's not) and that water condenses ( $CO_2$ dissolves in water poorly and very slowly). The main cause here is thermal expansion-contraction of air.

• home-experiment
• physical-chemistry

• $\begingroup$ Is there a stackexchange for chemistry? Maybe they could provide better help. $\endgroup$ –  Lemon Commented Jan 4, 2012 at 1:58
• $\begingroup$ @jak Not yet. $\endgroup$ –  Manishearth Commented Mar 15, 2012 at 7:21
• $\begingroup$ @Manishearth Yes there is - chemistry.stackexchange.com It is in beta, though. $\endgroup$ –  Dave Coffman Commented Jul 28, 2014 at 22:06
• $\begingroup$ @DaveCoffman look at the date on that comment. I moderate Chem.SE, I know about it :P $\endgroup$ –  Manishearth Commented Jul 28, 2014 at 22:28
• $\begingroup$ Geez - Sorry about that. $\endgroup$ –  Dave Coffman Commented Aug 2, 2014 at 18:19

3 Answers 3

I found two web pages that explain the phenomenon quite well, and even looks into the misconceptions people have.

The candle flame heats the air in the vase, and this hot air expands. Some of the expanding air escapes out from under the vase — you might see some bubbles. When the flame goes out, the air in the vase cools down and the cooler air contracts. The cooling air inside of the vase creates a vacuum. This imperfect vacuum is created due to the low pressure inside the vase and the high pressure outside of the vase. We know what you're thinking, the vacuum is sucking the water into the vase right? You have the right idea, but scientists try to avoid using the term "suck" when describing a vacuum. Instead, they explain it as gases exerting pressure from an area of high pressure to an area of low pressure. A common misconception regarding this experiment is that the consumption of the oxygen inside of the bottle is also a factor in the water rising. Truth is, there is a possibility that there would be a small rise in the water from the flame burning up oxygen, but it is extremely minor compared to the expansion and contraction of the gases within the bottle. Simply put, the water would rise at a steady rate if the oxygen being consumed were the main contributing factor (rather than experiencing the rapid rise when the flame is extinguished). (1)

The page from Harvard goes into more detail on the argument versus the error for the incorrect statement.

Argument : Oxygen is replaced by Carbon dioxide. So, there is the same amount of gas added than taken away. Therefore, heat alone most be responsible for the water level change. Source of the Error : A simplified and wrong chemical equation is used, which does not take into account the quantitative changes. The chemical equation has to be balanced correctly. It is not true that each oxygen molecule is replaced by one carbon dioxide molecule during the burning process; two oxygen molecules result in one carbon dioxide molecule and two water molecules (which condense). Remember oxygen is present in the air as a diatomic molecule. [A reader clarifies the water condensation in an email to me as follows: If the experiment were done with the sealing fluid able to support a temperature greater than 212 F and the whole system held above this temperature then the water product of combustion would remain gaseous and the pressure within the vessel would increase as a result of three gaseous molecules for every two prior to combustion and the sealing fluid would be pushed out.] Argument : Carbon dioxide is absorbed by the water. Thats why the oxygen depletion has an effect. Source of the Error : This idea is triggered from the fact that water can be carbonized or that the oceans absorb much of the carbon dioxide in the air. But carbon dioxide is not absorbed so fast by water. The air would have to go through the water and pressure would need to be applied so that the carbon dioxide is absorbed during the short time span of the experiment. Argument : The experiment can be explained by physics alone. During the heating stage, air escapes. Afterwards, the air volume decreases and pulls the water up. Source of the Error : the argument could work, if indeed the heating of the air would produce enough pressure that some air could leave. In that case, some air would be lost through the water. But one can observe that the water level stays up even if everything has gone back to normal temperature (say 10 minutes). No bubbles can be seen. Argument : It can not be that the oxygen depletion is responsible for the water raising, because the water does not rise immediately. The water rises only after the candle dims. If gas would be going away, this would lead to a steady rise of the water level, not the rapid rise at the end, when the candle goes out. Source of the Error : It is not "only" the oxygen depletion which matters. There are two effects which matter: the chemical process of the burning as well as a physical process from the temperature change. These effects cancel each other initially. Since these effect hide each other partially, they are more difficult to detect. (2)

It clearly has more to do with the temperature differences than any conversion of gases. Especially considering that a volume of oxygen and carbon dioxide will be nearly identical to human eye observation.

• 4 $\begingroup$ I'd trust Harvard (second footnote I am guessing). $\endgroup$ –  Skava Commented Jan 4, 2012 at 3:11
• 2 $\begingroup$ Yes "Skava", now go to bed! $\endgroup$ –  Larian LeQuella Commented Jan 4, 2012 at 3:12
• 3 $\begingroup$ This answer is useful in pointing the best explanation I've seen (the second link), but the text is plainly copied other pages (should be formatted as quotes) and does not make clear the general summary/conclusion. $\endgroup$ –  leonbloy Commented Jan 4, 2012 at 13:49
• $\begingroup$ I'd question one thing from that answer, though: Nowhere is a vacuum created. There's always air in the glass, and it always fills the whole space not occupied by water. When the air cools down, it doesn't contract by itself, only its pressure goes down (intuitively: Since the molecules get slower, they hammer less onto the water surface). As result the water is pressed more in by the air outside than out by the air inside, and thus flows inside. This rising water compresses the air inside, which causes air density and thus pressure inside to rise again until equilibrium is reached. $\endgroup$ –  celtschk Commented Jan 18, 2012 at 5:47
• 1 $\begingroup$ The second quotation seems to contradict the first one: first says "you might see some bubbles", the second one: "No bubbles can be seen". $\endgroup$ –  Ruslan Commented Jul 4, 2018 at 9:25

I have not actually tried this experiment, but I will make at least a few observations:

Hypothesis 1: The burning of oxygen is responsible for the reduced air pressure.

Prediction - if the burning of oxygen is the sole cause of the change in pressure, we should expect to see the water in the glass rise at a more or less constant rate from the moment the environment is sealed until the burning stops. After the candle extinguishes, there should be no more change in water level.

Hypothesis 2: The reduction in temperature after the candle extinguishes is responsible for the reduced air pressure.

Prediction - if the temperature change is the sole cause of the change in pressure, we should expect to see no change in water level while the candle is burning (in the limit that the glass was lowered very slowly). After the burning stops, the water should rise at a rate related to the temperature drop and eventually stop as the experimental setup comes to room temperature.

In order to test which explaination is correct, you should be able to merely perform the experiment and match the observation with the prediction. Of course, in real life it may be a combination of these two factors or perhaps include other reasons not listed here.

Additional measures such as putting an oxygen indicator in the glass (say a fresh slice of apple) or a thermometer would provide further insight.

• 1 $\begingroup$ As oxygen is burned - how many moles of CO2 do you get for each mole of O2 used? $\endgroup$ –  Martin Beckett Commented Jan 3, 2012 at 23:15
• 1 $\begingroup$ @MartinBeckett: Not to mention it's mostly carbon monoxide because it's imperfect burning. $\endgroup$ –  Mike Dunlavey Commented Jan 4, 2012 at 3:15
• 1 $\begingroup$ @MartinBeckett: The pertinent equation seems to be something like $C_{25} H_{52} + 38 O_2 => 25 C O_2 + 26 H_2 O$. So for 1 mole of oxygen we have 0.65 moles of $C O_2$ - a moderate reduction, and this assuming water condenses. $\endgroup$ –  leonbloy Commented Jan 4, 2012 at 14:40
• 1 $\begingroup$ @leonbloy - although with a smoky candle you do get a lot of CO. Plus since O2 is only 20% of air it would at most be a (1-0.65)*0.21 = 7% change in volume even with full combustion $\endgroup$ –  Martin Beckett Commented Jan 4, 2012 at 16:26
• $\begingroup$ @MartinBeckett: you are right, of course. See the Harvard link in the other answer for the complete picture. $\endgroup$ –  leonbloy Commented Jan 4, 2012 at 16:36

I will make this into an answer because the idea behind this question is used in an ancient medical metho d which was still used by practical nurses and even prescribed by old fashioned doctors when I was a child more than half a century ago in Greece. It is now used in alternative medicine practices

The air inside the cup is heated and the rim is then applied to the skin, forming an airtight seal. As the air inside the cup cools, it contracts, forming a partial vacuum and enabling the cup to suck the skin, pulling in soft tissue, and drawing blood to that area.

I think it was the invention of antibiotics which diminished rapidly its use, which was mainly for bronchitis pneumonia and similar afflictions, at least in Greece.

As far as the question goes, no liquids to confuse the issue of its being a strongly temperature dependent effect.

• $\begingroup$ Indeed, the practice is known as "cupping" and is often offered at spas and other health resorts. $\endgroup$ –  AdamRedwine Commented Jan 4, 2012 at 13:15
• $\begingroup$ +1 In spanish: "ventosa". I've seen it applied by my grandmother many years ago. $\endgroup$ –  leonbloy Commented Jan 4, 2012 at 13:37

Not the answer you're looking for? Browse other questions tagged water home-experiment physical-chemistry or ask your own question .

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WATER-CANDLE EXPERIMENT TO TRY OUT WITH KIDS

The water-candle experiment is a great early science activity to try out with kids. We tried it with our almost 3-year-old many many times and he insists almost daily to repeat it.

If you want to know more about the science behind, you can read here (Harvard.edu).

Safe science experiments at home are a great way to ignite the natural curiosity of your little one early on. We chose this one, because Aiden loves water and fire. And it did not include any explosion or mess.

So, well worth to try it out! Here is what you need.

Materials for the Water-Candle Experiment

To do it at home, we used few things from our kitchen:

• A clear glas bowl filled with some water.
• A tea light
• Small glas jar

Instructions

And that’s how it worked.

First, we placed the clear glas bowl with the water on his activity table. We divided the responsibilities – I was the one responsible to light up the tea light and place it into the water and Aiden was the one who covers the burning candle with the glas jar. Perfect!

After some seconds, the candles starts to dim and goes out. When the candle goes out, the water rises into the glas jar. The water level stays up for few minutes more, if your impatient toddler does not take the glas jar first and asks you over and over to repeated it again.

This simple science water-candle experiment for kids, has at least two aspects – a chemical and a physical one. Both a chemical and a physical reasoning are needed to explain what we can see. I found it a little bit challenging to explain it to my toddler, so we just enjoyed the science in action over and over again.

Here is a short video of one of our scientific sessions.

Happy Experimenting!

If you need more activity ideas, here is where you can find them !

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STEM Little Explorers

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Home » Articles » STEM » STEM Science » Candle in the vacuum experiment

Candle in the vacuum experiment

Today we will play with the fire – but won’t get burned (hopefully). let’s explore what happens when we put a glass over a burning candle that is surrounded by some water. it looks like magic, but as always it’s only science.

SCIENCE BEHIND CANDLE IN THE VACUUM EXPERIMENT

Let’s talk about the candles. Why does a candle burn? Well, you know that it won’t start burning by itself – we must supply some energy. And that’s precisely what we do when we use lighter or matches to lit the candle up. The chemical reaction that occurs is called combustion. Vax from the candle reacts with an oxygen to produce energy – heat, and light .

As a product of that reaction, carbon dioxide forms as well as some steam and of course smoke . Smoke is actually a bunch of small carbon particles that didn’t burn in the process, mixed with the steam.

Okay, so we learned that to sustain fire we need oxygen . When we cover our candle with the glass we are cutting off the oxygen supply. When the air in the glass is depleted of oxygen – lights out!

But why did the water rise? Heat from the candle made the air inside the candle quite hot and hot air expands to take more space. When the flame is out, the air starts to cool and that means it’s shrinking again. That produces a partial vacuum – the area of low pressure. The pressure outside of the glass (atmospheric pressure) is now higher than that in the glass. So water inside the glass quickly rises to make up the difference. Equilibrium!

All you need is some Water, Glass, Plate, Candle and a lighter.

• Water (with some food coloring for the better effect)

INSTRUCTIONS  FOR CANDLE IN THE VACUUM EXPERIMENT:

For step-by-step instructions on how to conduct this experiment watch the video at the beginning of the article or continue reading…

• Put the candle in the middle of the plate and lit it
• Pour the colored water (around 2 dl) on the plate so it surrounds the candle
• Cover the candle with the glass
• Watch carefully!

WHAT WILL YOU DEVELOP AND LEARN:

• Chemistry principles
• What are the atmospheric pressure and partial vacuum
• How to use the scientific method

If you liked this experiment and want even more cool stuff to do, we recommend making a lava lamp or growing your own sugar crystals .

If you’re searching for some great STEM Activities for Kids and Child development tips, you’re on the right place! Check the Categories below to find the right activity for you.

Click for more great STEM Science activities for kids

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Click here if you want to find out more about Child psychology and Child Development

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Candle Under Glass Experiment

• October 24, 2019
• 3-4 Year Olds , 5-6 Year Olds , 7-9 Year Olds , Chemistry , Fire Science , Household Items , Rainy Day Science , Science

We did this cool candle and glass experiment last week. The experiment teaches of role of oxygen in fire and its presence in the air. This one takes less than 5 minutes to complete it.

5 – 6-year-old kids can experiment this by noting time and they can learn how much oxygen is required to burn the candle. They can learn about smoke and wax.

How to do this candle and glass experiment

The simplest experiment to do but has a big science behind it. Don’t panic this science is easy for even kids to understand. Let us first do this experiment and study the science behind it.

Materials required for carrying out the experiment

• Candle Lighter or Matches
• Drinking glass
• Ceramic dinner plate or wooden board (optional)

[*Product links are affiliate links. Your support is highly appreciated]

Arrangement

Place the candle on the plate. Keep the matchbox and glass tumbler ready.

Light the candle and leave it for some time and then close the candle with a glass tumbler so that you can see through the light.

After a few seconds, you can see the flame comes down slowly and eventually goes off. You can try opening the glass when the flame is low to see how it picks up oxygen again and the flame goes higher.

You can also see a small sediment of moisture in the inner walls of the glass. That is a proof that fire releases H2O.

Yes, the experiment is over. Now, try these and share your experience with us.

• Now you can do this using a stopwatch and check the time taken for the light to go off after closing the candle with glass.
• Use the candle of different size and check the timing.
• Also, use bigger and smaller glass to check the timing.

Do this experiment with kids and allow them to make the observations.

Therefore oxygen is required for the candle to burn for a long time.

Detailed science with terminologies

Hydrocarbons present in the wax are converted to carbon dioxide and steam and this chemical process is called combustion. The oxygen gets pulled at the bottom and the wick draws the fuel. This will provide heat at the top and that makes air hot to rise up. This is how a candle burns. The steam part gives the blue color to the fire. The unburned carbon deposit makes the walls nearby black. Better oxygen means brighter the flame. Match stick is required to ignite and that produces the activation energy to start the entire burning process.

The chemical equation for your reference

Methane (hydrocarbon) + Oxygen –> Carbon dioxide and Water

CH4 + 2 O2 –> CO2 + 2 H2O

Check scienceline for more science facts.  Also, read candles.org explanation to master the science behind candle and science experiments.

When the candle is placed in the jar it limits the flow of oxygen and hence the candle flame goes off.

Oxygen is the fuel for wax and makes the wick burn. When the candle is closed with the glass jar the oxygen supply is stopped. Initially, the candle burns by making use of the oxygen within the glass and slowly when there is no oxygen the flame goes off.

The candle that is the shortest will go out first. It is because the CO2 is denser than air so it will settle down at the bottom eventually putting off the fire.

Glass is also prone to crack and break due to heat. Check out for heat resistant glassware and use them for this experiment.

When the candle is lighted the heat of the flame will melt the wax first near the wick that is on the top. Thus the wax will melt and that liquid wax gets drawn up again by the wick due to capillary action. The flame’s heat vaporizes the wax in the liquid state and that will initiate the hydrocarbon break down process. The hydrocarbon breaks down further into molecules of carbon and hydrogen.

Combustion is the chemical reaction happening in the candle burning process. Wax is derived from petroleum and is a carbon chemical and it reacts with the oxygen present in the air. This process creates CO2 which is a colorless gas.

Yes and no. Yes if it is pure beeswax. No, if it is not a pure wax. Candles made of pure beeswax will produce no smoke and cleanses the air around. It does this by releasing negative ions in the air. Such released negative ions bind with the toxins and remove them eventually from air. Also, natural pure beeswax burns slowly, when compared to paraffin candles and hence they last for long time.

Candle burning requires oxygen and that is present in the air naturally. When we close the candle with jar, then oxygen flow is limited and once all the oxygen present is exhausted the candle gets extinguished.

Overall, stay around and explain to them to have fun.

What inspired me to do this experiment?

Let me share my experience in how did I arrive at doing this experiment? During one summer we had a massive power failure. My little ones had never been used to such a situation ever. But this time the situation was tough and they had to spend the whole night without power. That is when I lit a candle for light while we had dinner.

As usual, my curious elder daughter asked me how does a candle burn. Why does it not require electricity as lights and fan do? How come it gives brightness as an electric bulb does. She bombarded me with questions I was like feeling glad that she thinks all these things. At the same time, my naughty little younger one as usual in her style started doing fun things. She blew the candle and sang “happy birthday”. 

We finished dinner and suddenly my little one using her empty glass covered the candle. In a few minutes the candle went off. I lighted the candle and told her not to play with fire. Again in few mins when I was away she did the same job to check if the light goes off.  It did go off and my elder one was puzzled to know why it happened.

Her question was when there is more air candle goes off that’s exactly what happens when we blew the candle. But here the contradiction happens and when the candle is closed it should not go off as airflow is cut. Then why it happens. I told her that there is a science behind that action.

Now, we started doing this experiment to explain the concept to the kids.

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Burning Candle Experiment With Water: Watch The Smokey Glass “Suck” Water In!

Cover a burning candle with glass and the surrounding water goes up inside the glass.

This burning candle experiment with water is pretty neat and one that will amaze many kids.

If you like quick experiments that you can do without buying a science kit for kids , this one is a good one to start with.

Before we move on, just a little reminder. This educational activity uses fire, so adult supervision is recommended.

With that out of the way, vamos a empezar! (Let’s start!)

oxygen, air pressure, candle experiments, water experiments

Doing This Experiment In The Gally Kids Headquarters!

As usual, we started this activity with colored water.

This is optional. But you get to see the water better when it’s a different color.

We chose  red.

Then we followed the instructions which are all straightforward.

The first try wasn’t exactly a success as there was very little water that went  into the glass.

We gave it another try and this time, it was a lot better. It was what we wanted and expected.

Then of course, we couldn’t stop there. We wanted to see if more water would get in if we put in another source of heat. So we put the lighted match in with the candle.

There didn’t seem to be much of a difference in the water level.

The smokey effect is pretty cool.

So we were happy with it.

Burning Candle Experiment With Water Materials

You will need:

• water (colored ones are the best)

Burning Candle Experiment With Water Procedure

• First, pour water into the plate.
• Next, put the candle in the middle of the plate.
• Then, light up the candle. Wait 30-seconds to 1 minute to make sure the candle is properly burning.
• When it’s ready, cover the candle with the glass.
• The candle will continue burning for a few seconds. But then when the candle turns off, this happens.
• The water rises inside the glass!

Why Does The Water Rise In The Candle Experiment?

The water rises in this candle because of air pressure.

But that’s not all there is to it.

What happens is that when you cover the candle with the glass, the air inside it expanded because of the heat. But then when the candle burned off, the air inside it got colder. Cold air contracts so this left a space inside the glass. This also allowed the air inside the glass to have less pressure.

But, the air outside has more pressure. So it pushes the water in until the pressure inside and outside are the same.

Pretty cool and fun activity that educates as well!

Video: Water Rises Up Inside The Glass

Here’s the video of the burning candle experiment with water which we posted on our Gally Kids channel in Youtube . Don’t forget to visit us there! And if you want to get notified every time we post a new video, make sure you subscribe!