CHEMISTRY FORM 1
- 1.1 What is matter?
- 1.2 What is Chemistry?
- 1.3 What does matter consist of?
- 1.4 Are the particles in matter stationary?
- 1.5 Arrangement, distance, and attraction between particles
- 1.6 Properties of matter (volume, shape and compression)
- 1.7 Conductors and non-conductors
- 1.8 Sources of heat
- 1.9 Bunsen burner
- 1.10 Role of Chemistry in society
- 2.1 Pure substances
- 2.2 Mixtures
- 2.3 Separation of Mixtures
- 2.4 Separation of solid-solid mixture
- 2.5 Separation of insoluble solid-liquid mixture
- 2.6 Separation of soluble solid-liquid mixture (solution)
- 2.7 Separation of immiscible liquid-liquid mixture
- 2.8 Separation of miscible liquid-liquid mixtures (solution)
- 2.9 Separation of liquid-gas mixture
- 2.10 Selecting and using appropriate methods of separating mixtures
- 2.11 Kinetic theory of matter
- 2.12 Classification by physical states
- 2.13 Effect of heat on physical states
- 2.14 Effect of impurities on melting and boiling points
- 2.15 Permanent and non-permanent changes
- 2.16 Definitions, chemical symbols and equations
- 3.1 Simple acid-base indicators
- 3.2 Universal indicators and pH scale
- 3.3 Reactions of acids with metals
- 3.4 Reactions of acids with carbonates and hydrogen-carbonates
- 3.5 Reactions of acids with bases
- 3.6 Effects of acids on substances
- 3.7 Applications of acids and bases
- 4.1 Composition of Air
- 4.2 Fractional distillation of liquid air
- 4.3 Rusting
- 4.4 Oxygen
- 4.5 Burning of substances in air
- 4.6 Atmospheric pollution
- 5.1 Candle wax and water
- 5.2 Reactions of metals with liquid water
- 5.3 Reaction of metals with steam
- 5.4 Preparation of hydrogen gas
Introduction to Chemistry: Bunsen burner
1.0 Introduction to Chemistry
1.9 Bunsen burner
What are the main parts of a Bunsen burner?
Materials and substances required
- Bunsen burner
- Gas supply and match box
- Study the following photograph of a Bunsen burner.
Labelled drawing of a Bunsen burner
- How many parts of a Bunsen burner can you see?
- Study the labelled drawing of a Bunsen burner to learn its parts. Why should the base be wide?
- Open the video below how to light a Bunsen burner
(courtesy Youtube - steps to light a Bunsen burner by SASS Chem) and learn the procedure for lighting a Bunsen burner.
Explain why, when lighting a Bunsen burner, it is necessary to:
- Check gas taps to be sure none of them had been left open
- Open all the windows and allow a few minutes to elapse before lighting a Bunsen burner.
- Close the air hole (using the collar) before opening the gas tap
- Hold a burning splint (or match stick) at the mouth of the chimney and open the gas tap at almost the same time.
- Open the air hole after lighting the gas.
Answers to Questions 1.9(a)
The main parts of a Bunsen burner are the base, gas inlet, gas jet, collar and chimney.
Base: Supports the burner to stand upright
Gas inlet: Allows gas into the Bunsen burner
Gas jet: Sucks air into the Bunsen burner
Collar: Controls amount of air entering the Bunsen burner
Chimney: Space for the gas to mix with air before it (gas) burns
What are the parts and characteristics of a luminous flame?
Open the video on luminous flame below.
(courtesy of Youtube ‐ Comparing different Bunsen burner flames by Science Web SciWeb Project). Study Part 1 keenly.
Note that a luminous flame is produced when the air hole of a Bunsen burner is closed.
- What is the major colour of this flame?
- Why do you think it is described as luminous?
- How many parts of this flame can you see?
- Name the parts of this flame according to their colours.
- Draw and label the diagram of a luminous flame as seen in the video.
- Why should the collar be closed for this flame to occur?
- In what ways is this flame similar to a candle flame?
- From your knowledge of a candle flame or this demonstration, is luminous flame hot?
- What is the black substance that readily deposits on the test tube?
- What is responsible for the major colour identified in Question 1?
- Is luminous flame suitable for heating? Give a reason.
Answers to Questions 1.9(b)
Do all parts of a luminous flame have the same temperature?
Observe the video, hotness of a candle flame and answer the questions that follow.
- Draw and label a diagram to represent the observation.
- From what is observed, is the paper burnt uniformly?
- What does the observation or diagram show about hotness of parts of a luminous flame?
Notice that in all cases, we cannot see what is burning. Even in a candle, burning and flame occur around the wick and not on the wax or its melt. What burns is invisible. It is a gas. We therefore define a flame as a mass of burning gases.
Answers to Questions 1.9(c)
A luminous flame:
- Is produced when the air hole is closed.
- Is bright and mainly yellow.
- Produces soot because of incomplete combustion (burning) of carbon.
- Is relatively cool and therefore not suitable for heating.
- Is quiet, unsteady and easily swayed by wind.
- Has three (3) parts: a small blue zone at the base, colorless zone at the mouth of the chimney, and bright (luminous) yellow as the main colour).
What are the parts and characteristics of a non-luminous flame?
Non-luminous flame is produced when the air hole is fully open, by turning the collar. Watch the video of a non-luminous flame
(courtesy Youtube-Comparing different Bunsen burner flames by Science Web SciWeb Project) and note its effect on the test tube and content being heated. Compare the flame with the picture that follows.
- What is the major colour of a non-luminous flame?
- Luminous means has the ability to produce light. Why do you think the flame is described as non-luminous?
- How many parts of this flame can you see?
- Describe them.
- Draw and label the diagram of a non-luminous flame as seen in the picture.
- Why should the collar be fully open for this flame to occur?
- In what ways is this flame similar to the flame of a gas cooker or stove?
- From your knowledge of a cooker or stove flame, is non-luminous flame hot?
- State five differences between non-luminous and luminous flame.
- When turning off a non-luminous Bunsen flame, it is important to screw the collar and cover the air hole first. Give a reason for this.
- State two similarities between a luminous flame and non-luminous flame.
Answers to Questions 1.9(d)
Labelled drawings of luminous and non-luminous flames
Firewood and charcoal burners produce mixed luminous and non-luminous flames. The luminous part has less heat and produces unburnt carbon (soot) that soils cooking utensils, coating them black. Also it pollutes the environment. A good heating burner produces a blue or pale blue (non-luminous) flame, which is hot.
Use of Bunsen burner (non-luminous flame)
- Laboratory experiments normally use non-luminous flame, and not luminous flame. Explain.
- Study the picture of a wire gauze, tripod stand and clay triangle which are normally used with a Bunsen flame when heating a substance.
- The arrangements for heating are typically as follows.
- Study diagram (b) showing the heating of a test tube in a Bunsen flame.
- How would you protect yourself and neighbors when heating a liquid in a test tube (or boiling tube)?
- Overheating one part of a test tube can cause it to crack, especially when heating a solid. How would you protect the test tube when heating a solid in it?
- Suggest two reasons why a wire gauze is not used in the set-up in (c).
The wire gauze is a wire net made of hardened steel, with ceramic or asbestos cover (the white substance) around the centre. A beaker is not heated directly but through the ceramic, which spreads the heat uniformly across the base. What is the risk of non-uniform heating of a glass beaker or any glass vessel?
(a) Heating in a beaker
(b) Heating in a test tube
(c) Heating in a crucible
What property of hardened steel wire gauze do you think makes it suitable for use with hot flames as indicated in (a)?
Watch the video, heating substances in a test tube, to learn how to heat the contents of a test tube.
(courtesy Youtube - Heating substances in a test tube by David Read)
Answers to Questions 1.9(e)
To simplify diagrams, we normally use a single upward arrow to represent heating (and Bunsen burner) and two such arrows to indicate strong heating. Besides, all other diagrams are two-dimensional. For example, a beaker is represented simply as a rectangle with an open top.
A candle flame is sometimes used for lighting, because it is bright, but not for heating. Heating vessels are held at the hottest parts of the non-luminous flames-neither too low nor too high above the cooker.