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The Bunsen burner is the standard apparatus for heating in a Chemistry school laboratory
It was discovered by the German Scientist Robert Wilhelm Bunsen in1854
aDiagram of a Bunsen burner
A Bunsen burner uses butanelaboratory gas as the fuel The butanelaboratory gas is highly flammable and thus usually stored safely in a secure chamber outside Chemistry school laboratory It is tapped and distributed into the laboratory through gas pipes
The gas pipes end at the gas tap on a chemistry laboratory bench If opened the gas tap releases butanelaboratory gas Butanelaboratory gas has a characteristic odorsmell that alerts leakagesopen gas tap
The Bunsen burner is fixed to the gas tap using a strong rubber tube
The Bunsen burner is made up of the following parts
i Base plate to ensure the burner can stand on its own
iiJeta hole through which laboratory gas enters the burner
iiiCollarsleeveadjustable circular metal attached to the main chimneyburell with a side holeentry It controls the amount of air entering used during burning
ivAir hole a holeentry formed when the collar side hole is in line with chimney side hole If the collar side hole is not in line with chimney side hole the air hole is said to be closed If the collar side hole is in line with chimney side hole the air hole is said to be open
vChimney tall round metallic rod attached to the base plate
bProcedure for lightingigniting a Bunsen burner
1 Adjust the collar to ensure the air holes are closed
2 Connect the burner to the gas tap using a rubber tubing Ensure the rubber tubing has no side leaks
3 Turn on the gas tap
4 Ignite the top of the chimney using a lighted match stickgas lighterwooden splint
5 Do not delay excessively procedure iv from iii to prevent highly flammable laboratory gas from escapingleaking
cBunsen burner flames
A Bunsen burner produces two types of flames depending on the amount of air entering through the air holes
If the air holes are fully open a non luminous flame is produced If the air holes are fully closed a luminous flame is produced If the air holes are partially open closed a hybrid of non luminous and luminous flames is produced
Characteristic differences between luminous and nonluminous flame
Scientific apparatus are drawn
i Using a proportional two dimension 2D crosssections Three dimensions 3D are not recommended
ii Straight edges of the apparatus on a scientific diagram should be drawn using ruler
iii Curved edges of the apparatus on a scientific diagram should be drawn using free hand
ivThe bench tripod or clamp to support apparatus which cannot stand on their own should be shown
CLASSIFICATION OF SUBSTANCES
Substances are either pure or impure A pure substance is one which contains only one substance
An impure substance is one which contains two or more substances A pure substance is made up of a pure solid pure liquid or pure gas
A mixture is a combination of two or more pure substances which can be separated by physical means The three states of matter in nature appear mainly as mixtures of one with the other
Common mixtures include
aSolutionssolidliquid dissolved mixture
Experiment
To make a solution of copper II sulphate VIPotassium magnateVII sodium chloride
Procedure
Put about 100 cm3 of water in three separate beakers Separately place a half spatula end full of copper II sulphate VI Potassium manganate VII and sodium chloride crystals to each beaker Stir for about two minutes
Observation
Copper II sulphate VI crystals dissolve to form a blue solution
Potassium manganate VII crystals dissolve to form a purple solution
Sodium chloride crystals dissolve to form a colourless solution
Explanation
Some solids liquids and gases dissolve in some other liquids
A substanceliquid in which another substance dissolves is called solvent
A substance solid gas which dissolves in a solvent is called solute
When a solute dissolves in a solvent it forms a uniform mixture called solution
A solute dissolved in water as the solvent exists in another state of matter called aqueous state Water is referred as the universal solvent because it dissolves many solutes A solute that dissolves in a solvent is said to be soluble Soluble particles uniformly spread between the particles of watersolvent and cannot be seen
Solute Solvent solution
Solute Water aqueous solution of solute
The solute dissolved in water gives the name of the solution e g
1 Sodium chloride solution is a solution formed after dissolving sodium chloride crystalssolid in water Sodium chloride exists in aqueous state after dissolving
Sodium chloride Water Sodium chloride solution
NaCls aq NaClaq
2 Ammonia solution is a solution formed after dissolving ammonia gas in water Ammonia exists in aqueous state after dissolving
Ammonia gas Water aqueous ammonia
NH3 g aq NH3 aq
3 Copper II sulphate VI solution is a solution formed after dissolving Copper II sulphate VI crystalssolid in water Copper II sulphate VI exists in aqueous state after dissolving
Copper II sulphate VI Water Copper II sulphate VI solution
CuSO4s aq CuSO4 aq
4 Potassium manganateVII solution is a solution formed after dissolving Potassium manganateVII crystalssolid in water
Potassium manganateVIIexist in aqueous state after dissolving
Potassium manganateVII Water Potassium manganateVII solution
KMnO4s aq KMnO4 aq
bSuspension precipitatessolidliquid mixture which do not dissolve
Experiment To make soil flour and Lead II Iodide suspensionprecipitate
Procedure
Put about 100 cm3 of water in three separate beakers Separately place a half spatula end full of soil maize and lead II Iodide to each beaker Stir for about two minutes
Observation
Some soil maize and lead II Iodide float in the water
A brown suspensionprecipitateparticles suspended in water containing soil
A white suspensionprecipitateparticles suspended in water containing flour
A yellow suspensionprecipitateparticles suspended in water containing Lead II iodide Some soil maize and lead II Iodide settle at the bottom after some time
Explanation
Some solid substances do not dissolve in a liquid They are said to be insoluble in the solvent When an insoluble solid is put in liquid
i Some particles remain suspendedfloating in the liquid to form a suspension precipitate
ii Some particles sinksettle to the bottom to form sediments after being allowed to stand
An insoluble solid acquire the colour of the suspensionprecipitate eg
1 A white suspension precipitate have some fine white particles suspended floating in the liquid Not white solution
2 A blue suspension precipitate has some fine blue particles suspended floating in the liquid
3 A green suspension precipitate has some fine green particles suspended floating in the liquid
4 A brown suspension precipitate has some fine brown particles suspended floating in the liquid
4 A yellow suspension precipitate has some fine yellow particles suspended floating in the liquid
c i Miscibles Liquidliquid mixtures
To form waterethanol and Keroseneturpentine miscibles
Procedure
iMeasure 50cm3 of ethanol into 100cm3 beaker Measure 50cm3 of water Place the water into the beaker containing ethanol Swirl for about one minute
iiMeasure 50cm3 of kerosene into 100cm3 beaker Measure 50cm3 of turpentine oil Place the turpentine oil into the beaker containing kerosene Swirl for about one minute
Observation
Two liquids do not form layers
Ethanol and water form a uniform mixture
Kerosene and turpentine oil form uniform mixture
Explanation
Ethanol is miscible in Water Kerosene is miscible in turpentine oil Miscible mixture form uniform mixture They do not form layers The particles of one liquid are smaller than the particles of the other The smaller particles occupy the spaces between the bigger particles
Immiscibles Liquidliquid mixtures
To form waterturpentine oil and Kerosenewater miscibles
Procedure
iMeasure 50cm3 of water into 100cm3 beaker Measure 50cm3 of turpentine oil Place the oil into the beaker containing water Swirl for about one minute
ii Measure 50cm3 of water into 100cm3 beaker Measure 50cm3 of kerosene Place the kerosene into the beaker containing water Swirl for about one minute
Observation
Two liquids form layers

The Bunsen burner is the standard apparatus for heating in a Chemistry school laboratory

It was discovered by the German Scientist Robert Wilhelm Bunsen in1854

aDiagram of a Bunsen burner

A Bunsen burner uses butanelaboratory gas as the fuel The butanelaboratory gas is highly flammable and thus usually stored safely in a secure chamber outside Chemistry school laboratory It is tapped and distributed into the laboratory through gas pipes

The gas pipes end at the gas tap on a chemistry laboratory bench If opened the gas tap releases butanelaboratory gas Butanelaboratory gas has a characteristic odorsmell that alerts leakagesopen gas tap

The Bunsen burner is fixed to the gas tap using a strong rubber tube

The Bunsen burner is made up of the following parts

i Base plate to ensure the burner can stand on its own

iiJeta hole through which laboratory gas enters the burner

iiiCollarsleeveadjustable circular metal attached to the main chimneyburell with a side holeentry It controls the amount of air entering used during burning

ivAir hole a holeentry formed when the collar side hole is in line with chimney side hole If the collar side hole is not in line with chimney side hole the air hole is said to be closed If the collar side hole is in line with chimney side hole the air hole is said to be open

vChimney tall round metallic rod attached to the base plate

bProcedure for lightingigniting a Bunsen burner

1 Adjust the collar to ensure the air holes are closed

2 Connect the burner to the gas tap using a rubber tubing Ensure the rubber tubing has no side leaks

3 Turn on the gas tap

4 Ignite the top of the chimney using a lighted match stickgas lighterwooden splint

5 Do not delay excessively procedure iv from iii to prevent highly flammable laboratory gas from escapingleaking

cBunsen burner flames

A Bunsen burner produces two types of flames depending on the amount of air entering through the air holes

If the air holes are fully open a non luminous flame is produced If the air holes are fully closed a luminous flame is produced If the air holes are partially open closed a hybrid of non luminous and luminous flames is produced

Characteristic differences between luminous and nonluminous flame

Scientific apparatus are drawn

i Using a proportional two dimension 2D crosssections Three dimensions 3D are not recommended

ii Straight edges of the apparatus on a scientific diagram should be drawn using ruler

iii Curved edges of the apparatus on a scientific diagram should be drawn using free hand

ivThe bench tripod or clamp to support apparatus which cannot stand on their own should be shown

CLASSIFICATION OF SUBSTANCES

Substances are either pure or impure A pure substance is one which contains only one substance

An impure substance is one which contains two or more substances A pure substance is made up of a pure solid pure liquid or pure gas

A mixture is a combination of two or more pure substances which can be separated by physical means The three states of matter in nature appear mainly as mixtures of one with the other

Common mixtures include

aSolutionssolidliquid dissolved mixture

Experiment

To make a solution of copper II sulphate VIPotassium magnateVII sodium chloride

Procedure

Put about 100 cm3 of water in three separate beakers Separately place a half spatula end full of copper II sulphate VI Potassium manganate VII and sodium chloride crystals to each beaker Stir for about two minutes

Observation

Copper II sulphate VI crystals dissolve to form a blue solution

Potassium manganate VII crystals dissolve to form a purple solution

Sodium chloride crystals dissolve to form a colourless solution

Explanation

Some solids liquids and gases dissolve in some other liquids

A substanceliquid in which another substance dissolves is called solvent

A substance solid gas which dissolves in a solvent is called solute

When a solute dissolves in a solvent it forms a uniform mixture called solution

A solute dissolved in water as the solvent exists in another state of matter called aqueous state Water is referred as the universal solvent because it dissolves many solutes A solute that dissolves in a solvent is said to be soluble Soluble particles uniformly spread between the particles of watersolvent and cannot be seen

Solute Solvent solution

Solute Water aqueous solution of solute

The solute dissolved in water gives the name of the solution e g

1 Sodium chloride solution is a solution formed after dissolving sodium chloride crystalssolid in water Sodium chloride exists in aqueous state after dissolving

Sodium chloride Water Sodium chloride solution

NaCls aq NaClaq

2 Ammonia solution is a solution formed after dissolving ammonia gas in water Ammonia exists in aqueous state after dissolving

Ammonia gas Water aqueous ammonia

NH3 g aq NH3 aq

3 Copper II sulphate VI solution is a solution formed after dissolving Copper II sulphate VI crystalssolid in water Copper II sulphate VI exists in aqueous state after dissolving

Copper II sulphate VI Water Copper II sulphate VI solution

CuSO4s aq CuSO4 aq

4 Potassium manganateVII solution is a solution formed after dissolving Potassium manganateVII crystalssolid in water

Potassium manganateVIIexist in aqueous state after dissolving

Potassium manganateVII Water Potassium manganateVII solution

KMnO4s aq KMnO4 aq

bSuspension precipitatessolidliquid mixture which do not dissolve

Experiment To make soil flour and Lead II Iodide suspensionprecipitate

Procedure

Put about 100 cm3 of water in three separate beakers Separately place a half spatula end full of soil maize and lead II Iodide to each beaker Stir for about two minutes

Observation

Some soil maize and lead II Iodide float in the water

A brown suspensionprecipitateparticles suspended in water containing soil

A white suspensionprecipitateparticles suspended in water containing flour

A yellow suspensionprecipitateparticles suspended in water containing Lead II iodide Some soil maize and lead II Iodide settle at the bottom after some time

Explanation

Some solid substances do not dissolve in a liquid They are said to be insoluble in the solvent When an insoluble solid is put in liquid

i Some particles remain suspendedfloating in the liquid to form a suspension precipitate

ii Some particles sinksettle to the bottom to form sediments after being allowed to stand

An insoluble solid acquire the colour of the suspensionprecipitate eg

1 A white suspension precipitate have some fine white particles suspended floating in the liquid Not white solution

2 A blue suspension precipitate has some fine blue particles suspended floating in the liquid

3 A green suspension precipitate has some fine green particles suspended floating in the liquid

4 A brown suspension precipitate has some fine brown particles suspended floating in the liquid

4 A yellow suspension precipitate has some fine yellow particles suspended floating in the liquid

c i Miscibles Liquidliquid mixtures

To form waterethanol and Keroseneturpentine miscibles

Procedure

iMeasure 50cm3 of ethanol into 100cm3 beaker Measure 50cm3 of water Place the water into the beaker containing ethanol Swirl for about one minute

iiMeasure 50cm3 of kerosene into 100cm3 beaker Measure 50cm3 of turpentine oil Place the turpentine oil into the beaker containing kerosene Swirl for about one minute

Observation

Two liquids do not form layers

Ethanol and water form a uniform mixture

Kerosene and turpentine oil form uniform mixture

Explanation

Ethanol is miscible in Water Kerosene is miscible in turpentine oil Miscible mixture form uniform mixture They do not form layers The particles of one liquid are smaller than the particles of the other The smaller particles occupy the spaces between the bigger particles

Immiscibles Liquidliquid mixtures

To form waterturpentine oil and Kerosenewater miscibles

Procedure

iMeasure 50cm3 of water into 100cm3 beaker Measure 50cm3 of turpentine oil Place the oil into the beaker containing water Swirl for about one minute

ii Measure 50cm3 of water into 100cm3 beaker Measure 50cm3 of kerosene Place the kerosene into the beaker containing water Swirl for about one minute

Observation

Two liquids form layers