MYP 6

MYP 6: Scheme of work


Topics index

6. Laboratory techniques

6.1 Safety in the laboratory
6.2 Laboratory apparatus
6.3 Testing substances

3. Materials and mixtures

3.1 Materials around us - Science world 1, p50
3.2 Synthetic and natural
3.3 Natural materials
3.4 Metals
3.5 Rocks: Investigating limestone
3.6 Rocks: classifying
3.7 Salt
3.8 Pure water
3.9 Chromatography



6. Laboratory techniques

6.1 Safety in the laboratory

Objective: To introduce the students to a new and potentially hazardous environment and explain safe practice.

Introduction:

Discuss the need for specialised apparatus for the handling of chemicals and materials.

Potential Chemical Hazards:
Toxic by skin absorption and inhalation.
" acute (immediate effect) poisons e.g. cyanide, chlorine gas
" chronic (accumulative effect) poisons e.g. lead and heavy metal compounds
" carcinogens (explain as chemicals whose effects may appear years later as cancer)
Corrosive
Skin irritants - allergens
Flammable liquids

Demonstrate some examples from the chemical store:
" Toxic: Lead salts
" Flammable: 5 drops cyclohexane on a watch glass and ignite using a splint
" Corrosive: Piece of magnesium ribbon into 10cm3 sulphuric acid.
" Oxidant: Potassium peroxodisulphate
" Explosive: Picric acid

Symbols used to convey information about chemicals:

 
Flammable
Corrosive
Explosive
Oxidising (helps other things to burn)
Toxic
Harmful or irritant
Environmental hazard


Reference: http://www.itcilo.it/english/actrav/telearn/osh/ip/symbols.htm

Emphasise that the scientist's job is to be able to handle these materials safely and link this with the laboratory rules:

" Always use the correct apparatus
" Always take appropriate safety precautions (safety glasses, fume cupboard etc)
" Always report and clean up spillages appropriately (certain materials need to be cleaned up in a specific way)
" Always follow instructions
" Never eat or drink in the laboratory
" Wash hands after handling chemicals

Class activity

Draw hazard symbols in exercise books and explain what each one means.



6.2 Laboratory apparatus

Objective: To introduce and familiarise the students with the apparatus and equipment used in the study of chemical science and its correct use


Activity 1- Worksheet SR page72

The students should classify each piece as apparatus for measuring, containing, supporting, delivering liquid, heating, testing etc. This may be done as a class discussion.

Written activity

Tabulate the information by drawing each piece of apparatus in the exercise book in 2 dimensions (ruler and pencil) with labels and its purpose.

Example:

Apparatus
name
use
sizes

 


Conical flask Containing liquids 50cm3
100cm3
250cm3
500cm3

 

 

Beaker Containing and pouring (delivering) liquids 50cm3
100cm3
250cm3
400cm3

 

 

 

 

     

The lesson may be completed by selection of apparatus from a choice and explaining its purpose. The students may be instructed for example to collect 50cm3 of water in a 250cm3 conical flask.


6.3 Testing substances

Objective: To introduce the concept of testing as applied to chemical substances and materials

Introduction

The concept of a test should be introduced as a means of obtaining information about the nature of a material.

Materials tests to involve three stages (before - during - after):
1. observation and recording before
2. observation and recording during the application of some aspect (change)
3. observation and recording after.

Students to have explained the procedure of recording the test.

What is done
What is seen (B,D,A)

Activity- student

1. Add 1 spatula of copper carbonate to 25cm3 of sulphuric acid in a small beaker with stirring.

Observations possible

Before: Sulphuric acid clear - colourless liquid
Copper carbonate - green powder

During: Effervescence (bubbling)
Green copper carbonate powder dissolves

After: Blue clear solution

Write-up: Criterion B- communication



3. Materials and mixtures

3.1 Materials around us - Science world 1, p50-5

Introduction

Five major classes of materials, each one chosen for its properties. Discuss properties and reasons for using materials.

Activity 29 pp 112-3:

Classification of materials - Science World 1, p50
Make list with reason for type of material used. Indicate whether it's man made or natural.

Questions page 51.



3.2 Synthetic and natural

Activity 30 pp114-5:

Comparing synthetic and natural fibres.


3.3 Natural materials

Introduction - discussion

What were the original resource materials for all tools and building. What tools did the first humans need and what did they use for survival. What properties did they need their tools to have? - wood and plant products, animal products, bone, hair, stone.

Activity: Classwork

Make a list of the needs of a tribe of hunter-gatherers in ancient times (pre iron-age)
Alongside the needs suggest what materials they could have used giving a reason.

Key words: hard, light, strong, sharp, heavy, rigid, waterproof, flexible.

Activity:

Plan the design of a bow and arrow for hunting, using materials available in ancient times.
Draw your bow and arrow with labels.
Write an explanation of why you chose that material for each part.
What products were available for ancient man to use?
What were the properties needed for each part?

" Bow - strong and flexible
" Arrow- strong, light and rigid
" Arrow flights: light and flexible
" Arrowhead- strong, heavy and sharp
" Bowstring - flexible, elastic, strong and thin.

If you were to design a bow and arrow using modern materials what would you use?


3.4 Metals

Introduction

Discussion about the extraction of metals from rocks - Bronze age, Iron age (p52) and alloys.

Activity - student

Investigate the similarities and differences between wooden splints (or lolly sticks if possible), balsa wood, ebony (or similar) and similar sized clean strips of copper, zinc and lead.

Suggestions have a series of experiments around the room for the students to rotate and test the following:

" Hardness (scratch test, each trying to scratch the other)
" Strain resistance (weights hung vertically)
" Rigid strength (weights hung laterally)
" Density (water)
" Lustre (polish)
" Conductivity (meter)

Write-up - Criterion B - communication

Data collection - tabulate results
Conclusion - properties of metals and wood
Evaluation - were the tests fair, how could they be improved.




3.5 Investigating limestone

Introduction

Limestone is one of the most important types of rock in the world. Ciudad Encantada in Cuenca, North and South Downs in the UK etc.


White Horse Hill in Oxfordshire - the grass has been removed by Iron-age man to reveal the chalk surface below. The symbol of a horse can be seen for miles around.

Cerne Abbas Giant is a similar carving in the South Downs

White rock often called chalk (not the same as blackboard chalk) chemical name Calcium Carbonate.
Used in the manufacture of iron, fertilizers etc


Activity 32 pp118-120

Other investigations.

" Investigate the change in mass when a piece of limestone is heated strongly.
" Place the strongly heated limestone in water and test its acidity (basicity) using pH paper.
" Try to make soap form a lather in the water - a dirty grey solid appears (scum) - this is an example of "hard water" a problem in limestone areas for water systems, boilers and kettles.


3.6 Investigating and classifying rocks

Introduction

Igneous, sedimentary and metamorphic rocks. Explain the formation of each with examples and diagrams.
" Igneous - molten rock from volcanic sources - granite, gneiss
" Sedimentary - layers of cretaceous period sea organisms (limestone), layers of sand (sandstone), layers of smaller alumina based particles (clay)
" Metamorphic - derived from molten pressurised sedimentary rock. Clay produces slate, limestone produces marble.


Activity 33 pp123-125




3.7 A very important mineral (Salt)


Introduction (science world 60-61)

Where does salt come from?

Activity

Growing salt crystals

write-up Criterion B - communication

 

Activity

Separation of salt from water

Write-up Criterion F - experimental

Discuss methods of finding out if the distillate contains salt. Evaporate a little of the original solution in an evaporating basin and repeat using a sample of the distillate. Have a full scale distillation apparatus set up in the laboratory and demonstrate it at the end of the lesson. The students should be able to draw the apparatus in 2 dimensions with pencil and ruler and labels.


3.8 A very important substance - Pure water


Introduction

Activity One World

This activity is very important in the modern world as approximately half the worlds population does not have enough water for thier daily needs (see reference material ). I suggest a One-World approach researching various populations where water supply is either scarce, polluted or too salty or isn't controlled efficiently (monsoons). The students could prepare a poster presentation focussing on a particular country of their choice.

Round off by discussing the different methods available for water purification with the pros and cons of each one.





Activity



3.9 Chromatography


Introduction


Activity

 


 
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Copyright: 2003 Isis Publication