Burning Questions About a Candle

Activity: Observations of a Burning Candle

Purpose

Materials Needed

• Candle
• Lighter or Matches
• Notebooks or Paper for Each Student to Record Data
• Writing Utensil
• Small pan or non-flammable surface to collect dripping wax

Procedure:

Attached here is a printable form that has most of the questions and directions below, but with space for you to write in your answers and observations while you work. Have fun!

Observations to make before you light the candle

Answer the following questions concisely. That is, use short sentences or sentence fragments, and only say what really needs to be recorded. You may want to work in pairs or small groups, each writing down observations, then periodically comparing notes and asking each other questions. If you do it this way, just remember: don't make critical comments! Be critical in your thinking, in the sense of always asking yourself "What does that mean anyway?" and not in the sense of "That's clearly wrong" or "What a dumb observation." Be positive in your approach, focus on the candle, and keep asking yourself questions in your own mind, especially questions that lead to further observations and more questions.

1. Give a physical description of the candle and its components. What are the individual parts and what are they made of?
2. How is the candle shaped? Why?
3. At what angle do you plan to burn the candle? Why?

Do some physical "tests" on the candle using what you have on you or laying around the room. What do these tests tell you about its properties?

Do any of these tests give you an indication of the nature of the candle components at the molecular level? What do you know about the chemical nature and/or composition of these components?

Hypothesize what will happen when you light the candle and start it burning

Write down what you think will happen in terms of the observations you made above, especially with respect to the molecular level. Start a new page and be complete but concise.

Now, light the candle and watch what happens

In your notebook, record all the observations you can make regarding the lighting and burning of the candle. For this first set of observations, don't worry about asking questions so much as just making as many quick notes as you can. You should plan on spending a fair amount of time on this (more than a minute and less than an hour or two).

Hints:

• It is important that you record your observations as quickly as you can and then come back to some of them later for further thought and extended observation.
• As you look at the candle, try to separate the components into the individual elements. The flame is different from the vapor which is different from the wick and the solid and liquid wax.
• There are processes in dynamic equilibrium occurring during the burning process. Think about these processes and ask yourself questions. There are physical changes occurring as well as chemical reactions. Try to imagine what these are, list them, and ask questions about them.
• Your "observations" should also contain conjecture and hypotheses about what is occurring or why it is occurring. It is crucial that you have some of these extensions of the observation process recorded.
• Try to make at least 10 distinct and separate observations initially. (Be aware that individual observations numbering over 100 have been recorded by others.)

It may take you a while to begin to think about what is happening. Be patient and work at the process. Once you begin to see how to ask questions related to what you are seeing, a snowball effect will occur that should open up whole new areas of observation for your critical consideration. Be sure to write down all of your thoughts and observations as they occur. Don't try to be critical of the material you write down, but simply put it down as quickly as possible. You will have plenty of opportunity later for evaluation and grouping of your data.