BUNSEN BURNER
(new version)
Activity No. 2
A Bunsen burner (named after its inventor, Robert Bunsen) is a laboratory
device designed to heat substances for various experiments. It consists of a metal tube
on the base with a gas inlet at the lower end of the tube which has an adjusting
controller (gas control valve); openings in the sides of the tube can be regulated by the
collar to admit as much air as desired. The mixture of air and gas (optimally about 1
part gas to 3 parts air) is forced by gas pressure to the top of the tube where it is ignited
with a match. It burns with a pale blue flame, the primary flame seen as a small inner
cone, and a secondary flame, almost colorless flame seen as a larger outer cone, which
results when the remaining gas is completely oxidized by the surrounding air. The
hottest part of the Bunsen flame, which is found just above the tip of the primary flame,
reaches about 1,500°C (2,700°F). With too little air, the gas mixture will not burn
completely (incomplete combustion) and will form tiny carbon particles that are heated
to glowing, making the flame luminous. With too much air, the flame may burn inside
the burner tube; that is, it may strike back.
Figure 1. The Bunsen burner
The production of flame depends on the intake of the fuel gas (methane,
CH4) and particularly, of oxygen. The burning of the fuel gas which produces a non-
luminous flame (colored blue) indicates that there is enough amount of oxygen that
goes through the burner and thus, would favor the complete combustion of the fuel gas.
This is represented by the following chemical equation:
CH4(g) + 2O2(g) CO2(g) + 2H2O(l) + heat
The production of a luminous flame (yellow color) is an indication that
oxygen is insufficient for the burning of the fuel gas; therefore, there is an incomplete
combustion, as signified by the balanced equation below. The process below indicates
that solid carbon (soot) is formed.
2CH4(g) + 3O2(g) C(s) + CO2(g) + 4H2O(l) + heat
OBJECTIVES:
1. To identify the parts and explain the functions of the Bunsen burner.
2. To differentiate between luminous and non luminous flames through
the colors and relative hotness of the flames.
Apparatus, Chemicals and Other Materials:
2pcs 250mL beaker solid powder charcoal
1pc Bunsen burner
1pc tongs
1pc 100mL graduated cylinder
1pc porcelain dish
1pc watch glass
1pc wire gauze
1pc iron stand
1pc iron ring
PROCEDURE:
1. Examine closely the Bunsen burner and be acquainted with the parts. Draw the
Bunsen burner and label its parts.
2.The following procedure describes the proper way of lighting the Bunsen
burner: connect the other end of the rubber tubing to a gas outlet, check the gas
valves if it is open. Set the air holes partially open, hold a lighted match above the
burner and then turn on the valve/gas outlet slowly until a 6-8 cm flame is
obtained.
3.Close the air holes by turning the collar and observe the appearance of the
flame, Label it FLAME A, using a tongs hold for a few seconds a porcelain over
this flame. Observe.
4.Measure carefully 50mL tap water with the use of graduated cylinder and pour
it into a 250 mL beaker. Place a beaker on top of the iron ring with wire gauze,
cover it with a watch glass and heat the water to boiling using FLAME A, note the
time required to boil water, record it.
5.Open the air holes of the burner gradually until the burner starts to roar, too
much air will make the burner roar and cause the flame to snap out. Adjust the
air holes until the roaring just stops. With the air holes properly adjusted,
sufficient amount of oxygen mixes with the fuel gas in the barrel. In this kind of
flame there should only be two distinct concentric cones visible. Label this flame
as FLAME B. Also place a piece of clean porcelain over this flame and observe.
6.Again boil 50mL of water using FLAME B and note the time required to boil the
water.
7.Spray a pinch of powdered charcoal on FLAME B, note the color change of the
flame.
8.Insert an unused matchstick quickly in each of the following regions: a.just
above the tip of the barrel, b.tip of the inner cone, c.tip of the outer cone. The
results will give the relative hotness of the different regions of the flame.
9.Turn off the gas slowly until the flame “strikes back”, now the flame has gone
down the barrel. This occurs when there is too large proportion of air in the gas
mixture being burned. Notice that the lower part of the burner soon gets hot.
Whenever the flame strikes back turn off the gas and allow the burner to cool
before lighting it again after partly closing the air holes.
Name: Date Performed:
_________________
Section & Group: Date Submitted:
Instructor: Remarks: ______________________
BUNSEN BURNER
Experiment No. 2
DATA AND RESULTS:
1. Draw Parts of the Bunsen burner and label it
OBSERVATIONS
2.
Type of Color Luminosity Deposit on Time for
Flame (Luminous or porcelain boiling
non-luminous) (+) or (-)
Flame A
Flame B
3.Give the name and formula of the black deposit on the bottom of the porcelain
material
Name: ________________
Formula: ______________
4.Give the color of the flame when a pinch of charcoal was sprayed on it
___________________
5.What kind of flame (luminous or non luminous) fits the observation in number 4.
___________________
6.Based on the results in procedure 8, label the regions of the flame as hot, hotter,
hottest
______________
______________
______________
QUESTIONS
7.Match the following parts of the Bunsen burner with their functions, write only the
letter in the space provided:
PARTS FUNCTIONS
________barrel A.supports the burner
________gas spud B.regulates the air intake
________base C.where the mixing of oxygen and fuel gas
occurs
________air hole D.passage way of oxygen
________collar E.passage way of fuel gas
F.controls the fuel gas intake
8.From the differences in the length of time of boiling, which flame produces more heat
per given time?
_____________________________________
9.Which kind of flame is more economical? Why? (2pts)
______________________________________________________________________________
______________________________________________________________________________
10.Based on your results, in what region of the flame (inner cone or outer cone) can one
find:
a.the unburned carbon ______________________
b.the unburned fuel ________________________
11.Which kind of flame represents complete combustion?
_________________________________________
12.From the balanced reactions representing complete and incomplete combustions of
methane gas, what is the molar ratios of oxygen gas to methane gas:
a.in a complete combustion:
____________________
b.in an incomplete combustion:
___________________
Conclusion:
__________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
