CONTENTS
- HEAT SOURCES
- THE BUNSEN BURNER
- FLAMES
1.HEAT SOURCES
Are substance which produces heat energy . •They are also known as burners. •Burners uses fuel or electricity to produce heat energy. •When fuel burns they produce heat and light. What is heat?
Heat is a form of energy which brings about rise in temperature. •Thus, heat is simply the quality of being hot. There are two main types of heat sources: 1. Natural heat source .
This is a naturally occurring heat source. Example: the sun.
2.Artificial heat source
This is the man-made heat source. Example; Candle, Charcoal burner, Kerosene stove, Electric burner, Spirit burner, Gas stove, Bunsen burner Heat sources in the laboratory
i) Candle: Is the heat source which is made up with waxy materials, It gives yellow flame which is very bright. ii) Charcoal burner: Is the heat source that uses charcoal as the fuel. iii) Kerosene burner: Is the heat source that uses kerosene as the fuel. , It gives a blue flame which is very hot and can be regulated.
iv) Electric burner: Is the heat source that uses electric energy to produce heat energy,It gives very high amount of heat and can easily be regulated.But electric burner is limited to the regions where electricity is available. v) Spirit burner: Is the heat source which uses the spirit as the fuel.It gives yellow flame which give bright light.when alcohol used as a fuel it is called alcohol burner vi) Gas stove: Is the heat source which uses gaseous fuel .It gives blue flame which is very hot and can be regulated.
v) Bunsen burner: Is a small adjustable heat source that is connected to the gas source.It was discovered scientist called Robert Bunsen 1885.
SOME PICTURES OF SOURCES OF HEAT IN THE LABORATORY  |
| Alcohol burner |
 |
| Spirit burner |
 |
| Kerosene burner |
Most experiments carried out in chemistry require some
heating. It is therefore very important to have good heating tools. The common
heating apparatus used in laboratory is a Bunsen burner. It is originated by
the name of the owner Robert Bunsen 1885THE DIAGRAM OF BUNSEN BURNER
Bunsen burner has six parts, which are
1. Base 2. Gas hole 3. Pipe point jet 4. Air holes 5. Collar 6. Chimney (barrel)
1. Base 2. Gas hole 3. Pipe point jet 4. Air holes 5. Collar 6. Chimney (barrel)
1. Base –it gives stability to Bunsen burner.It is due to its heavy weight when placed on bench. 2. Gas hole/gas in-let tube-lets the gas on from the gas supply. 3.Jet-Directs the gas to the barrel. 4.Collar-Regulates the amount of air entering the burner so as to get the required flame. 5.Air holes-These are holes allow air (oxygen) in to support burning of gas. 6. Chimney-is a part of the burner where air from outside and gas from gas supply mix up and burn.
How to light a Bunsen burner Connect the Bunsen burner by a rubber tube to the gas supply. Close the air holes. Turn the gas tap on to let in sufficient gas. Quickly bring a flame at the top of the barrel. Turn the collar to adjust the air holes until you get a type of a flame you want. Adjust the gas tap until the gas supply enough to produce a non luminous flame.
NOTE;To put off the flame of the burner after you finish heating a substance turn the gas tap off in order to cut off the gas supply to the burner. ◦Never turn on the gas tap before starting up the flame.
VIDEO ON HOW TO LIGHT BUNSEN BURNER
Flame is a region of
burning gases that gives out heat and light. It
◦The flame is formed when fuel burns. The color and amount of heat produced when the fuel burns depends on the fuel and the heat source.
◦The flame is formed when fuel burns. The color and amount of heat produced when the fuel burns depends on the fuel and the heat source.
Types of flame
i) Luminous flame
◦Is a flame which gives
out bright-yellow light.
◦The flame is sooty and yellow color because the oxygen supplied is not enough to complete burning of the fuel.
◦The flame is sooty and yellow color because the oxygen supplied is not enough to complete burning of the fuel.
◦It consists four
parts (zones)
(i) Thin outer
zone
(ii) Luminous and yellow
zone
(iii) Zone of unburnt
gas
(iv)Blue or green zone
DIAGRAM OF LUMINOUS
FLAME
Examples of luminous
flame
1. Coal gas flame
2. Kerosene lamp flame
3. Fire wood flame
4. Candle flame
5. Tin lamp flame
Characteristics of a luminous flame
Characteristics of a luminous flame
5. It is unstable.
6. It is not very
hot.
7. Has a wavy
shape.
◦Non luminous flame is
the flame which is blue in color.
◦In the Bunsen
burner luminous flame is formed when the air holes are opened.
◦It consists three
parts (zones)
(i) Pale
purple-blue zone
(ii)Blue-green
middle zone
(iii) Colorless
inner zone (Un-burnt gas zone)
Diagram of
non-luminous flame
Characteristics of
non-luminous flame
1. It is blue in
color.
2. It is noisy.
3. It has three
zones.
4. It does not form soot.
5. It is steady (stable)
6. It is very hot.
7. Has a triangular shape.
Example of Non–luminous flame
1. Kerosene stove flame
2. Gas burner flame
3. Oxy-acetylene flame
Uses of non-luminous flame
1. Used for heating purpose in
laboratory.
2. Used in welding.
3. Used at home for cooking.
4. Used in the flame test.
DIFFERENCES BETWEEN LUMINOUS FLAME
AND NON LUMINOUS FLAME
LUMINOUS FLAME
|
NON LUMINOUS FLAME
|
1. It is yellow in color
|
It is blue in color
|
2. It is quiet
|
It is noisy
|
3. It has four zones
|
It has three zones
|
4.It produce soot
|
It does not produce soot
|
5. It is unstable
|
It is stable(steady)
|
6. It is not so hot
|
It is very hot
|
7. It is wavelike flame
|
It is triangular flame
|
8. It gives bright light
|
It gives dim light
|
STRIKING BACK (BURNING BACK)
◦When a Bunsen burner is burning to
form a non-luminous flame and a gas tap is turned off slowly.
The supply of the gas is
reducing in the gas air mixture.
◦The mixture contains very little
gas and much air in such a way that mixture burns rapidly forming an explosion.
◦In this case the flame will be
accompanied by a pop sound. This is called burning back.
◦At this time the rate of burning
the gas is greater than the rate at which the gas rises up the barrel.
REVIEW QUESTIONS WITH ANSWERS
Form 2.ZEC 2016
8. (a)Define the following terms;
(i)Heat (ii)Flame
(b) Draw and label the Bunsen burner
(c) What type of flame will occur
when air holes of Bunsen burner?
(i) Are fully opened
(ii)Are closed
Answers
8. (a) (i)Heat is a form of energy which brings about rise in temperature.
(ii)Flame is a region of burning
gases that gives out heat and light
(b) THE BUNSEN BURNER
(c) (i) Non-luminous flame
(ii)Luminous flame
Form 2 NECTA 2016
5. (a) What are the five steps of
lighting up the Bunsen burner
Answer
Ø Connect the Bunsen burner by a rubber tube to the gas
supply.
Ø Close the air holes
Ø Turn the gas top on to let in sufficient gas
Ø Quickly bring a flame at top of the barrel
Ø Turn the collar to adjust the air holes until you get a type of a
flame you want.
Form 2 NECTA 2017
7. (a)Why a flame produced by spirit
lamp may not be good for heating in the laboratory?. Give two reasons
(b).name the type of flame produced by spirit lamp
Answer
(a)
i.
it produce soot
ii.
it is not very hot
(b) Luminous flame
Form 2 NECTA 2018
4. (b).By excluding Bunsen burner
mention other sources of heat that can be used in the laboratory
(c) why Bunsen burner is the best heat source in the laboratory-
Answers
(b)
i.
Candle
burner
ii.
Kerosene
burner
iii.
Spirit
burner
iv.
Electric
burner
v.
Alcohol
burner
(c) Because Bunsen burner provide
safe and efficient heat when used properly
