Chemistry 217 - Chemical Principles I
6. The Candle Experiment

Candle Experiment

Candle Experiments

Our statistics draw that the average chemistry student has not done laboratory experiments within the last five years. In this exercise, we will carry out simple kitchen chemistry experiments that will allow you to sharpen your observational skills and get some quick feedback on your laboratory report writing skills. Remember you do not need your all-home microlab kit to do any of these experiments.


Introduction

In the winter of 1859, Michael Faraday, a famous English scientist (see p. 827, Jones and Atkins, Molecules, Matter and Change, 4th ed.), gave several lectures centered around the chemistry and physics of a candle! Faraday would tell his listeners:

He would then proceed and set out to prove his point by lighting a candle and demonstrating all the processes involved. We will enter the lab portion of Chemistry 217 by that same door and will repeat some of the experiments that Mr. Faraday demonstrated more than a century ago. In so doing, we hope you will exercise your power of observation and sharpen some of your experimental skills to help prepare you for the more concentrated in-lab experiments you will be challenged with later on.


Materials Required

Theory

In burning a candle one starts with a solid fuel (wax), which is liquified, rising up into the wick by capillary action to be vapourized in the atmosphere, and then quickly oxidized by the candle flame. In burning, the candle produces energy in the form of heat and light. The burning process is a simple organic chemical reaction represented by the following equation:

If one were to remove the fuel (wax), the oxygen or the initiator (flame) or any combination of the three, the candle would go out. Professional fire-fighters use this idea constantly when they develop strategies for fighting fires. Figure CE.1 shows a detailed diagram of the flame of a burning candle and will give you a better idea of the mechanics involved.


Procedure


Note that formally observations and results or explanations for the observations are treated separately in a laboratory report. Since these experiments are rather simple, we will note our observations and
possible explanations for those observations in tabular form. You can
then incorporate this table into the short-report format described in the “Writing Laboratory Reports” section of this manual.
































Experiment
Observations
Results and Explanations
A. Reigniting a Candle
B. Water Suck Up
C. Extinguishing a Candle with Aluminum Foil
D. Candle Condensation
E. Extinguishing a Candle with Carbon Dioxide

1.Why did the candle reignite with a match held away from the wick?
2.a.Explain how the candle was extinguished with aluminum foil and carbon dioxide.
b.Suggest and explain another method to extinguish a candle not already used in Part A of this experiment.
c.Write out the balanced chemical equation for the reaction that produced carbon dioxide in this experiment.
3.What does the formation of water on the aluminum ice sack suggest about the chemistry of a burning candle?
4.a.Suggest a reason why the water is sucked up into the glass jar.
b.A candle flame will use up oxygen as it burns. However, the consumption of oxygen alone does not explain the observed volume change. What other factor(s) need to be considered?
5.Explain the difference in the shapes of the two flames shown on page 53 of this manual.