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Materials
Grade6, Unit 6M.3:
Changing materials
Unit 6M.3: Changing materials
Adding materials to water.
Chemical reactions
Skill you will use:
Classifying
Observing
Predicting
By the end of this unit you should:
Know that when substances are added to water, some
will react while others either dissolve or remain suspended.
Distinguish between reversible and irreversible changes
and know that reversible changes are physical and
irreversible ones involve chemical changes in which new
substances are formed.
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Materials
Grade6, Unit 6M.3:
Changing materials
Mixing materials to water
Many types of materials dissolve when
mixed into water, this forms a solution.
Salt is a soluble material, it dissolves in
water. A material that doesn’t dissolve in
water is called insoluble, for example sand.
A material that is insoluble creates a suspension when mixed
in water. A suspension is not clear, you cannot easily see
through it. As the large, insoluble particles settle you can
see the separate layers.
Physical changes in water are temporary and reversible
Some materials can react with water, like
sodium. Signs of a chemical change in
water are the presence of bubbles, change
in colour, light or heat, even a flame.
6.12.1, 6.12.2
Muddy water
particles are
suspended in
water making
it cloudy
The large mud
particles have
settled to bottom
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Materials
Grade6, Unit 6M.3:
Changing materials
Activity 1: Investigate what happens when a variety of
substances are added to water.
You will need:
Five 500 ml plastic bottles with caps
Teaspoon
Plastic funnel
Samples: sugar, dirt, tea leaves (cut
open a tea bag), flour, food colouring
Water and measuring beaker
Steps:
1. Use the funnel to add 1 teaspoon of each of the sample
to the empty plastic drink bottle.
2. Predict (P) what will happen to each sample after the
water is added:
Sugar……………………………………………………………………………………….…………..
………………………………………………………………………………………….…………………….
Dirt…………………………………………………………………………………………………………
…………………………………………………………………………………………………………………
Tea leaves……………………………………………………………………………………………
…………………………………………………………………………………………………………………
Flour……………………..………………………………………………………………………………
…………………………………………………………………………………………………………………
Food colouring………………………………………………………………………………………
…………………………………………………………………………………………………………………
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Materials
Grade6, Unit 6M.3:
Changing materials
2. Use the measuring beaker and funnel to add 250ml of
water to each plastic bottle and screw on the lid.
3. Observe (O) what happens to contents initially.
4. Now, shake each bottle until the contents are mixed.
5. Choose some key changes you observed to add to the top
line of the Attribute List Organiser (ie dissolved, suspended,
cloudy etc).
6. Record the changes that you observed for each sample by
placing ticks in the corresponding box. You can also draw
examples. Attribute List Organiser
Sample Change 1
………………………
Change 2
………………………
Change 3
………………………
Change 4
………………………
Sugar
Dirt
Tea
leaves
Flour
Food
Colouring
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Materials
Grade6, Unit 6M.3:
Changing materials
Observe (O): Other observations you want to comment on?
………………………………………………………………………………………………………………….
………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………
Explain (E): Did your observations match your predictions?
Did anything happen that you did not predict?
……………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………
Activity 2: Sort into a T-chart the following common kitchen
materials according to how they change when added to water
Milo, detergent, pepper, milk, salt,
juice, rice, coffee granules, cooking oil.
Dissolves Suspended
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Materials
Grade6, Unit 6M.3:
Changing materials
Changing Materials with Water:
1-Weathering is the process of breaking down a material
over time. There are two types of weathering; physical
weathering and chemical weathering.
Physical weathering erodes a
material over time, but the
properties of the material stay
the same.
Chemical weathering also breaks
down a material over time but it
changes the properties that the
material is made of. For instance,
a hard material may change to a
soft material after chemical weathering.
The time taken for the weathering process depends on the
properties of the material, the amount of water, the
movement/ action and the type of water.
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Materials
Grade6, Unit 6M.3:
Changing materials
2- Extracting colour: The colour
found in our soils and rocks, plant
leaves and flowers can be extracted
using water. If you collect a sample
of soft rock and scratch the surface to make a powder. Mix
the powder with water it can make a paint known as ochre.
Traditionally tribes used the ochre pigment for art.
3- Extracting scent: The natural
oils in plants, fruits and flowers
have a scent that can be
extracted using water. The
water is used to heat and reduce
down the liquid from the plant.
The liquid left produced in this
process has a fragrance that is
used for perfumes and fragrances.
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Materials
Grade6, Unit 6M.3:
Changing materials
Aerial Water Bombing
Foam Extinguisher
4- Putting out fires: Water has two main properties that
help put out certain types of fires.
Water when applied to a very
hot fire changes to steam, this
steam prevents the air getting
to the fuel thus putting out the
fire.
The water also cools the fuel
to below the ignition point
helping to put out the fire.
Water only helps for fires of
paper, wood or cloth/ material.
Other types of fires may need
chemicals to extinguish the
flame for eg. petrol.
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Materials
Grade6, Unit 6M.3:
Changing materials
Chemical Changes of Materials
A chemical change is when the atoms in a substance or
material link together to make a new substance. This is
known as a chemical reaction. The properties of the original
material have changed.
Chemical changes can be permanent and irreversible but
like physical changes they can also be reversible.
You can usually identify when a chemical change of a material
has taken place if:
- a gas or smell is given off
- there is permanent color change
- a new substance (e.g. rust) is formed and is visible
- the liquid changes temperature
- the solute is not recoverable when the water is left to
evaporate.
These children are studying chemical
reactions that make materials change
permanently.
The substances they start with are
called reactants. After the reactants
change, they form a new substance
called a product.
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Materials
Grade6, Unit 6M.3:
Changing materials
Activity 3: Observing a Chemical Reaction
You will need:
Plastic bottle, Baking soda, teaspoon, balloon, funnel,vinegar.
Steps:
1. Use the funnel to add 2 teaspoons of baking soda to the
balloon.
2. Tip a small amount of vinegar into the bottom of the
plastic bottle.
3. Attach the balloon to the top of the plastic bottle,
CAREFUL not to tip the contents in yet!
4. Draw a picture of what the experiment looks like BEFORE
in the box below.
5. Now tip the contents of the balloon, the baking soda into
the bottle.
6. Draw another picture of the experiment AFTER adding
the baking soda.
BEFORE
AFTER
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Materials
Grade6, Unit 6M.3:
Changing materials
What evidence do you have that the Baking soda and vinegar
experienced a chemical change?.....................
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
………………………………………………………………………………………………………………
Design your own experiment
using baking soda and vinegar to
demonstrate a chemical change.
Remember the scientific process
Show your experiment design
and planning to the teacher
before you test it out.
Write some initial ideas down
here:
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Materials
Grade6, Unit 6M.3:
Changing materials
Using electricity to change things: Water and solutions, particularly strong salt solutions or acid
solutions, like lemons are known as conductive substances.
This means that electricity flows through them easily.
Why cells and batteries eventually
run down when used?
A chemical cell converts chemical
energy into electrical energy. Most
batteries are chemical cells. A
chemical reaction takes place inside
the battery and causes electric
current to flow. This process is
known as electrolysis.
Research the “Lemon Juice
Electricity Experiment”
What are the procedures?
How does it work?
Test it out yourself!
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Materials
Grade6, Unit 6M.3:
Changing materials
Key Terms: Soluble/
insoluble
Dissolve
Suspension
Physical and
chemical change
Weathering
Permanent
Temporary
Key Ideas: Some materials when added to water
dissolve and others form suspensions.
Materials can have physical or chemical
change.
Sometimes change in some materials is
temporary and other times permanent.
Chemical changes can create new
substances.
Key Questions:
Q1 Complete this concept map for the word “Dissolve”
DISSOLVE
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Materials
Grade6, Unit 6M.3:
Changing materials
Q2. Amal added some substances to water and stirred them.
She noted her observations in the table below.
Substance Observation
1 - Sugar Dissolved
2 - Salt Dissolved
3 - Sand Remained at the bottom
4 - Stomach powder Bubbles of gas given off
5 - Flour Liquid turned white and eventually the white
substance collected at the bottom
What substances experienced chemical changes?
……………………………………………………………………………………………………………………….
b. How could Amal tell if it was a chemical change?
………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………..
c. Which two samples could the change have been physical or
chemical?............................................................
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Materials
Grade6, Unit 6M.3:
Changing materials
Q2: The two lists below contain raw materials and substances
made from them. Draw lines to connect each raw material to
the substance produced from it. On each line write whether
the change is a physical or a chemical one.
Raw material Substance produced
Clay Glass
Ore Metal
Sand Paper
Seawater Pottery
Wood Salt
Q3: Classify the list of changes as physical or chemical
change
A. Making yoghurt from milk. ---------------.
B. Making drink cans from aluminium sheet. -----------.
C. Boiling water in a kettle. -------------.
D. Boiling an egg. -----------.
E. Making a cup of tea. ---------------.
F. Using a torch cell. ---------------.
G. Burning a candle. ---------------.