West Lothian Council
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Oil, water and soap
Read
Oil and grease are the two main substances that
are difficult to clean from hair, skin or clothing
by washing in just water. This is because oil and
grease are insoluble in water. In the next
experiment you will find out how it can be made
easier to clean oil by using cleaning chemicals like
soap.
Collect
2 test tubes
1 test tube rack
1 beaker of water
1 bottle of oil
1 bottle of soap solution
2 rubber stoppers
1 dropper
Put the test tubes in a rack and half fill them with water.
Use the dropper to carefully put 5 drops of oil onto the top of
the water in each test tube.
oil
water
To one of the test tubes add 5 drops of soap solution.
Put the stoppers onto the tubes and shake each tube gently for
2 minutes then observe what has happened.
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Write a heading and try the work below.
1. The names of two substances that are difficult to clean from
hair, skin and clothing are __________ and ____________.
2. These substances difficult to clean using just water because
_____________________________________________.
3. Think about what happened in the experiment and answer the
following questions.
a) Oil did/did not dissolve in the pure water?
b) Oil did/did not dissolve in the soapy water?
c) Copy and complete the sentence below by circling the
correct answer.
Oil and grease cannot be cleaned with pure water but can with
soapy water because oil is soluble/insoluble in pure water but
soluble/insoluble in soapy water.
How cleaning chemicals work
Read
If we use cleaning chemicals like soap or detergent we can
remove oil and grease stains because grease and oil are soluble
in the cleaning chemicals. Cleaning chemicals work because they
have special molecules in them. These special molecules have a
certain shape. They look a bit like tadpoles.
The head part of the
molecule is soluble
in water but not in
oil.
The tail part of the
molecule is soluble
in oil but not in
water.
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When the oil and soapy water are shaken together the tails
from the soap get stuck into the oil and this breaks up the
grease and oil into tiny droplets. The tiny droplets can then mix
with water because the special molecules are soluble in both oil
and in water.
4. Draw a diagram to show the shape of the special molecules
that can be found in cleaning chemicals.
5. When oil is shaken with soapy water the tail of the soap gets
s________ to the oil and b______ u__ the oil into ______
______________.
6. Tiny droplets mix with water because the special molecules
are ___________________________________________.
7. Many everyday products contain cleaning chemicals. Look at
the display of everyday products and make a list of the names
of some products that contain cleaning chemicals. Add some
extra to your list if you can think of any others.
Products Containing Cleaning Chemicals
_______________________________________________
_______________________________________________
_______________________________________________
_______________________________________________
_______________________________________________
_______________________________________________
_______________________________________________
_______________________________________________
_______________________________________________
_______________________________________________
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Lathering – PPA 3
Read
You already know that when soaps and shampoos are
used to wash substances, they froth and foam up into
bubbles. The scientific word for this is lathering.
The aim of the next experiment is to see if the
volume of detergent affects how much lather is
made.
Now write a heading and do the work below in your jotter.
1. The scientific word for frothing and foaming is __________.
2. Complete the table below for your results during the PPA
volume of detergent (drops)
height of foam (mm)
result 1 result 2 average
Ask your teacher for the instruction sheet for unit 2 PPA3 and
carry out the experiment for changing the volume of
detergent. Fill in your table of results and answer the
questions below.
3. List some factors you had to keep the same to make the
experiment fair.
_______________________________________________
_______________________________________________
4. I knew how much foam was produced because ___________
_____________________________________________.
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5. Copy and complete the conclusion below by circling the
correct answer.
I found out that the higher the volume of detergent the more/less
foam was produced.
Ask your teacher for an assessment sheet and complete it.
Then show it to your teacher to check whether you have passed
the practical test.
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Hard water
Read
We are very lucky in Scotland to have good
quality water. Most of the water that we have
in Scotland is called soft water. In some parts
of Britain eg London, the water that they have
is called hard water. Hard water has more
chemicals in it than soft water. The hard
water that comes out of the taps in these places is safe to
drink but the chemicals it has in it can change how soaps work.
Write a heading and do the work below.
1. In Scotland we have hard/soft water.
2. The difference between hard water and soft water is that
hard water has more _________________ in it.
3. Collect experiment card 2.28 and before you start:
a) write down the aim of the experiment.
Aim: ________________________________________
____________________________________________
____________________________________________
b) Draw diagrams to show what you will do in the experiment
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4. Complete the table below as you do your experiment.
Contents of tube
soft water + soap
hard water + soap
soft water + soapless detergent
hard water + soapless detergent
did it make a lather or a scum?
5. Copy and complete the sentences below by circling the
correct answers.
When soap is used with hard water a scum/lather is made. To avoid
this happening, it is better to use soapy/soapless detergents when
you are cleaning with hard water.
Read
People who live in areas with hard water find it more
difficult to get a lather when they use cleaning
chemicals. This means that they end up spending
more money on products like shampoo because they
need to use more shampoo to get a good lather. It is
also more expensive to live in these areas because
the chemicals in the hard water can damage
appliances like kettles and irons. Many people who
live in these areas now have water purifiers attached to their
taps. These change the hard water into soft water. Or they
buy soapless detergent instead of soapy ones.
6. People who live in areas with hard water spend more money on
shampoo and kettles because ________________________
______________________________________________
7. Water purifiers change ________ water into ________
water.
8. The kind of detergent you would buy if you lived in an area
with hard water is called ________________ detergent.
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Dry cleaning
Read
When clothing is dry cleaned, this does not mean that no liquid
is used. It means that the liquid is not water. The liquids that
are used to dry clean clothes are special
solvents. These liquids are very good at
dissolving oil and grease stains.
Watch your teacher demonstrate what happens to vaseline
when it is put into two different solvents.
grease
water
special
solvent
after shaking
before shaking
Write a heading and try the work below.
1. The liquid which is not used when clothing is dry cleaned is
________________.
2. The solvents that are used in dry cleaning are special because
______________________________________________
3. Copy the diagram of the grease demonstration and complete
the diagram above to show what the test tubes looked like
after shaking.
4. Copy and complete by circling the correct word in the
sentence below.
Vaseline is soluble/insoluble in water but is soluble/insoluble in
the special solvent.
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Dissolving stains
Read
Many stains that we get on our clothes are not
soluble in water eg ink, lipstick, gloss paint, blood
and grass stains. This means that water cannot
be used to get these stains out. We need to use
a liquid that will dissolve these stains to be able
to clean the clothes.
Write a heading and do the work below.
1. List some examples of stains that are not soluble in water.
_______________________________________________
_______________________________________________
2. Complete the table below as you do the experiment.
name of
solvent
Is the stain soluble or insoluble?
biro
lipstick
paint
grass
meths
acetone
white spirit
Collect experiment card 2.30 and do the experiment. Record
your results in the table.
3. Which solvent or solvents would you use to remove
a) biro stains - __________________________
b) lipstick stains -________________________
c) paint stains - _________________________
d) grass stains - _________________________
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Clothing fabrics
Read
Clothes are made from fabrics. These fabrics can be either
natural or synthetic. Natural means that the fabric comes
from an animal of a plant. Synthetic means
that the fabric is man-made in the chemical
industry. Clothing fabrics are made from thin
strands called fibres. These fibres are made
from very big molecules called polymers.
Write a new heading and do the work below.
1. A natural fabric means ____________________________
_____________________________________________
2. A synthetic fabric means __________________________
_____________________________________________
3. Clothing fabrics are made from thin strands called _______.
4. These fibres are made from very big molecules called
_________________.
5. Collect the information card called clothing materials and do
the work below.
a) Complete the table to show whether each material is
natural or synthetic.
name of material
cotton
nylon
wool
leather
terylene
polyester
silk
natural or synthetic?
b) Cotton is good for summer T-shirts because _________
__________________________________________.
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c) Nylon is good for making ropes because ____________
__________________________________________
d) Wool is good for making winter clothing because ______
__________________________________________
e) Two disadvantages of leather are _________________
__________________________________________
f) Two advantages of using silk for making clothing are
_________________________________________
One disadvantage is __________________________.
Your teacher may now show you how to make nylon in the nylon
rope trick demonstration.
Changing fabrics
Changing the colour of fabrics
Read
Special compounds that are used to change the colour of
fabrics are called dyes. Bright coloured materials can be made
using dyes. Dyes are not new chemicals. Even people thousands
of years ago were using dyes to colour their clothes. They
made most of these dyes from plants. Nowadays we still use
plants to make dyes but we also have man-made ones too.
Write a heading and do the work below.
1. The special compounds that are used to change the colour of
fabrics are called ________________________________.
2. When man was using dyes thousands of years ago the dyes
were natural/synthetic.
3. Today we get dyes from _________ and use ____-made
dyes.
You might get a chance to find out more about plant dyes using:
http://www.pioneeringthinking.com/naturaldyes.html
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Your teacher may ask you to try to colour some fabric with dyes
from different plants.
Changing the properties of fabrics
Read
You will have heard of fabrics that are easy
iron, drip-dry, waterproof, breathable,
flameproof etc. To produce fabrics with
these types of properties they are treated
with special chemicals.
Flameproofing
Most house fires happen at night so children's
clothing is often treated with chemicals to make it
flameproof. The materials that are used to make
couches and curtains are also often flameproof.
Theatre curtains and scenery are treated with
flameproofing chemicals to prevent a fire spreading rapidly and
give people time to escape.
Breathable clothing
When people do sport their bodies often
produce sweat. Some fibres have special
properties to help absorb sweat. These
fibres can absorb sweat because the fibres
make strong bonds to water molecules and
pull the sweat away from the skin. Because
these fibres attract sweat they are hard to
drip-dry but they are comfortable to wear as
they do not make us feel sweaty. Cotton
and gortex are two examples of fibres that do this.
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Write a heading and do the work below.
1. Fabrics are treated with c____________to give them
special properties like flameproofing or easy ironing?
2. Children's night clothes are often flameproofed. This is done
because _______________________________________.
3. Theatre curtains and scenery are flameproofed because
_____________________________________________.
4. Some fibres absorb sweat from someone's skin because
_____________________________________________.
5. Breathable fibres are difficult to drip-dry because
_____________________________________________.
6. Two examples of the names of breathable fibres are
_____________________________________________.
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