INVESTIGATION OF A CANDLE FLAME
Chemistry is a basic science which deals with matter and energy relationships, the composition of matter, and
the changes matter undergoes. One factor that distinguishes chemistry as a science is the use of scientific methods to
solve problems. Scientific methods are organized, systematic ways to determine answers through experimentation.
In using scientific methods to solve a problem, observation, investigation, analysis, and interpretation are most
important.
As chemists, we investigate the properties and changes of matter using our senses and devices available in the
laboratory. We observe carefully during these investigations and record all findings. These observations are then
analyzed using such tools as organized data tables, graphs, and mathematical equations. Finally, we interpret our
observations by relating them to what we know from experience. These interpretations or conclusions can be used
to formulate theories.
This experiment is intended to help you become familiar with the scientific tools a chemist uses to solve
problems. You will observe a candle under a variety of conditions. You will also investigate the products formed by
the burning candle. You will organize your observations into tables that you should analyze carefully before making
your interpretations.
Objectives:
In this experiment, you will
- observe a burning candle as conditions are changed,
- test the behavior of the candle under a variety of conditions, and
- determine the products formed by a burning candle using a series of tests and observations.
EQUIPMENT
goggles and apron
candle (2 cm diameter, 10 to 12 cm long)
glass plate
aluminum foil to cover glass plate
balance
matches
beakers or jars (1000 mL and 600 or 2000 mL)
clock or watch with second hand or digital timer
glass tubing (10 mm diameter, 8 cm long)
test tube holder.
copper wire (30 cm)
dropper pipet
cobalt chloride test paper (2 pieces)
Erlenmeyer flask (250 mL), with rubber stopper
test tube (large, 18 x 150 mm)
thermometer
2. After completing Parts Band C, measure the mass of
the candle and holder again. Record.
B. The Behavior of a Candle Flame Under
Various Conditions.
1. Light the candle. CAUTION: Long hair or loose clothing
can swing into the candle flame. Invert a large beaker
(1000 mL) or jar over the burning candle (see Figure 11). Record the time (in seconds) required to extinguish
the flame.
PROCEDURE
A. Mass Change During Candle
Combustion.
1. Place a candle on a small glass square covered with
aluminum foil or on a candle holder supplied by your
teacher. Measure the mass of the candle and holder to
0.01 gram. Record the mass in your data table.
FIGURE 1-1. Procedure for Step B.1.
2. Relight the candle and repeat Step 1 using a beaker
that is either larger or smaller than the one used in
Step 1 (2000 or 600 mL).
3. Wind a piece of copper wire (about 30 cm long)
around a pencil to form a coil, leaving a 5 cm length
of wire for a handle. Remove the coil from the pencil
and relight.your candle. Using a TONGS, lower the
coil into the candle flame as in Figure 1~3. Record
your observations. Return the wire to the reagent
table.
5. Obtain a large test tube, test tube holder, and
thermometer. Half fill the test tube with tap water.
Check the temperature of the water and record. Using
the test tube holder, hold the test tube just above the
candle flame, as shown in Figure 1-4. CAUTION:
While heating do not point the open end of the test
tube at yourself or at other people. Check the water
temperature every 30 seconds while heating for a
total of two minutes. Record the temperature data
in your table.
X
CAUTION:
Do NOT use your hand to hold
the wire coil...Use Tongs
FIGURE 1-4. Procedure for Step C-5.
6. Extinguish the candle flame. When the candle is cool,
measure and record its mass. (See Part A, Step 2.)
FIGURE 1-3. Procedure for Step B-3.
C. Determination of Products Formed as a
Candle Burns.
1. Place a drop. of tap water on a piece of cobalt
chloride test paper. Record your observations.
2. While the candle is burning, invert a large beaker or
jar (1000 mL) over the flame for a few seconds. Test
any liquid formed in the beaker with cobalt chloride
test paper. Record your observations.
3. Examine the bottom of the beaker used in Steps 1
and 2 of Part B for any charred deposits. Record
observations.
4. CAUTION: Limewater causes burns; avoid skin and
eye contact. Invert the 250 mL Erlenmeyer flask over
the burning candle until the flame is extinguished.
Quickly remove the flask and place it upright.
Carefully add about 10 mL of limewater solution to
the flask. Stopper the flask, shake the solution, and
watch for changes in the solution. Carbon dioxide
gas causes limewater to turn cloudy. Discard the
limewater by rinsing it down the drain using plenty
of water.
Name: ___________________________ Period: ________ Date: ___________
Investigation of a Candle Flame
Part A: Investigation of Mass of Burning Candle
1. Initial Mass: ________________
2. Final Mass: ___________________
Why is there a loss of mass? _________________________________________
Part B: Investigation of Candle Flame
When you initially light the candle, which appears first? (circle one)
flame on wick
wax melts near wick
1. Time extinguished (large beaker): _____________
2. Time extinguished (small beaker): _____________
This experiment implies that one of the reactants for candle combustion is:
________________________________________________________________
3. Coiled wire in candle flame observation:
________________________________________________________________
Coiled wire is often used to remove heat from an object. Does the coiled wire
cause the flame to disappear after the wire has become very hot? ____________
What is the relationship between heat of the candle flame and the light emitted
from the flame?
________________________________________________________________
The excess smoke that appeared during the coiled wire experiment is due to
incomplete combustion, the result of inadequate heat to the burning vapor.
The coiled wire experiment showed that _______________ is necessary for
combustion.
Part C: Investigating the Products of a Burning Candle:
1. Results from Cobalt Chloride paper and water: ________________________
________________________________________________________________
2. Results from Cobalt Chloride paper and condensation from inside inverted
beaker:
________________________________________________________________
The results of the cobalt chloride paper suggest that _______________ is a
product of combustion.
3. The charred deposit in the beaker is carbon. Where did it come from?
________________________________________________________________
Results of the limewater experiment: ___________________________________
4. Limewater turns cloudy in the presence of CO2, carbon dioxide. Based on this
experiment what gas is produced as a product of candle combustion:
________________________________________________________________
5. Initial Temperature: _________°C
Temperature at 30 sec: ________ °C
Temperature at 60 sec: ________ °C
Temperature at 90 sec: ________ °C
The rise in temperature is due to heat energy from a chemical reaction. What
chemical reaction is producing the heat?
_______________________________
Analysis:
1)
Identify the three (3) reactants needed for candle combustion:
_________________
2)
___________________
List three (3) products that result from complete candle combustion:
_________________
3)
_____________________
_____________________
___________________
Which experiments are quantitative?
________________________________________________________________