National 4
Unit 1
Solutions
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Adapted from LCW Booklets
Solutions: Soluble or insoluble
Learning Intentions:
 A solution is made when a solute dissolves in a solvent
 When a solute dissolves in a solvent it is said to be soluble
 When a solute does not dissolve in a solvent it is said to
be insoluble
Some solids dissolve in water; others do not. If a solid dissolves in
water we say that it is soluble. If a solid does not dissolve we say
that it is insoluble.
What makes a Solution?
A simple solution is basically two substances that are going to be
combined. One of them is called the solute. A solute is the substance
to be dissolved (e.g. sugar). The other is a solvent. The solvent is the
one doing the dissolving (e.g. water). As a rule of thumb, there is
usually more solvent than solute. When the solute dissolves in a
solvent it makes a solution.
Answer in sentences
1. What does the word soluble tell you about a substance?
2. What does the word insoluble tell you about a substance?
3. What is a solute?
4. What is a solvent?
5. When a solute dissolves in a solvent what is made?
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Adapted from LCW Booklets
You are now going to find out whether some substances are
soluble or insoluble. Copy the table on the below before you
start.
Name of solid
(Solute)
soluble or
insoluble in the
water (solvent)
soluble or
insoluble in white
spirit (solvent)
Salol
Salt
Nickel chloride
Candle wax
Collect experiment card 13.1 and 13.2. Do experiment 13.1 first
then experiment 13.2. Fill in your table as you go along.
Answer the questions
1. How did you know that the solutes had dissolved?
2. What did you see if the solids (solutes) were insoluble in the
liquids (solvents)?
3. When salt is dissolved in water it made a salt solution. Was the
salt the solute or the solvent?
4. When salol was dissolved in white spirits it made a solution.
Was the white spirits the solute or the solvent?
5. List two things you did to make sure that the experiment was
fair.
6. Collect the sheet called ‘Making a Solution’ , fill in the blanks
and paste it in your notebook.
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Adapted from LCW Booklets
Success task
Describe how you would make a sweet cup of hot water using the
following words that you have learned
SOLUTE
SOLVENT
SOLUTION
SOLUBLE
Using the Data booklet
We can also use a data book to find out whether a substance is
soluble or insoluble.
Collect a data book and look at the contents page.
What page would you look at to find out about the solubility of
substances in water?
Success Task
Make a table with two headings; Substance and Solubility.
Add the list below under your Substance heading.
Then use the data booklet to find out if they are soluble or
insoluble.
Complete your Solubility column as you go.
calcium carbonate
potassium carbonate
calcium nitrate
copper chloride
potassium nitrate
iron phosphate
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Adapted from LCW Booklets
sodium sulphate
magnesium chloride
calcium sulphate
copper phosphate
Use the data book to explain what you would see if you added
magnesium phosphate to water.
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Adapted from LCW Booklets
Making a Saturated Solution
Learning Intention:
 A saturated solution is made when no more solute will
dissolve in a solvent.
Making a solution is easy. You have already done this in experiments
13.1 and 13.2. All you do to make a solution is dissolve a solute in a
solvent (liquid).
When no more solute can dissolve the solution is called saturated.
Some substances are more soluble than others, so a lot of the solid
can be dissolved before the solution is saturated.
Write a heading try the work below
1. Describe what you need to do to make a solution.
2. What does it mean is a solution is saturated?
3. Tony had two samples of solids called A and B. He wanted to find
out whether solid A was more soluble than solid B.
He filled two test tubes
with some water and
started to add spatulas o
solid A to one test tube
and solid B to the other
test tube. After each
addition he shook the
tubes and checked if the
solid dissolved.He continued to add the solids until no more could
dissolve. His results are shown in the following table.
A
Solid (Solute)
A
B
Adapted from LCW Booklets
B
number of spatulas to
make a saturated solution
5
8
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a)
b)
Which solid was the most soluble?
List two things he would have done to keep the experiment
fair.
4. You are now going to find out about the solubility of three
different compounds.
a)
Copy and complete the table below by doing experiment 1.14.
Name of solid
b)
number of spatulas to
make a saturated solution
Copy and complete the following sentences.
The results of my experiment show that all/not all solids
dissolve equally. The most soluble solid was __________
and the least soluble solid was __________.
c)
List two things you kept the same to keep the experiment fair.
Success Task
Collect half a sheet of graph paper and draw a bar graph of your
results.
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Adapted from LCW Booklets
Concentration of Solutions
Learning Intentions:


The concentration of a solution tells us how much solute has
been dissolved.
Solutions can be described as being either dilute or
concentrated.
Before we learn about how concentration can change the speed of
reactions we need to understand what the concentration of a
solution is.
The concentration of a solution tells us about how much solid solute
has been dissolved in a solvent. The amount of the solid is not
measured in weight but it is measured in units called moles. Just
like time is measured in units called minutes, concentration is
measured in units called moles per litre (also written as mol/l)
If one mole of salt is dissolved in one litre of water we say it has a
concentration of 1 mole per litre.
One mole of
solute (salt)
One litre of
solvent (water)
Salt solution,
concentration = 1
mole per litre
If two moles of salt is dissolved in one litre of water we say it has a
concentration of 2 moles per litre(2 mol/l)
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Adapted from LCW Booklets
The more salt dissolved in the water the greater the
concentration of the solution.
The concentration of all solutions can be measured in moles per
litre, eg, some of the acids you used in S2 experiments had a
concentration of 1 mole per litre. A solution that has a
concentration of 2 moles per litre is more concentrated that a
solution that has a concentration of 1 mole per litre.
To turn a concentrated solution into a dilute one we can add water.
Answer the following questions.
1. What does the concentration of a solution tell us?
2. What units is concentration measured in?
3. Describe how you would make a salt solution that has a
concentration of 2 moles per litre. You may use a diagram if you
wish.
4. Copy and complete the sentence below.
The more solute dissolved in a solvent the
_______________the concentration.
5. Which solution is the most concentrated?
A
1.5 mol/l
B
3.0 mol/l
6. Which solution is the most dilute?
A
0.1 mol/l
B
2.5 mol/l
7. What would you add to a concentrated acid if you wanted to
dilute it?
8. If water is added to an acid will the concentration of the acid be
higher or lower.
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Adapted from LCW Booklets
A concentrated solution has more substance dissolved in it than a
dilute solution.
Experiment: Dilute and concentrated solutions
Collect:
 a tub of copper sulphate
 two boiling tubes in a rack
 a 100cm3 measuring cylinder
 a beaker of water
 a spatula
 a stopper
 a dropper
Instructions:
1. Measure out 30cm3 of water into each boiling tube.
2. To the first boiling tube add one spatula of copper sulphate.
3. To the second tube add three spatulas of copper sulphate.
4. Use the stopper and shake each tube until the copper sulphate
dissolves.
Answer the following questions.
1. What is the difference between a concentrated solution and a
dilute solution?
2. Draw the two boiling tubes and colour them in to show what
happened in the experiment.
Now use a dropper to add water to the bluest tube and try to get
the blue colours the same in each tube.
3. Copy and complete the sentences on the next page.
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Adapted from LCW Booklets
To make a concentrated solution we need to dissolve
more/less solid. To turn a concentrated solution into a
dilute solution we need to add _________.
Investigation The speed of dissolving
Learning Intention:
 To investigate if the temperature of water affects the
speed of dissolving.
Collect a copy of the sheet called PPA1 and use the investigation
write up sheet to report your findings.
Success Task
Complete the Investigation write up sheet.
Did you Know?
You will have heard the word dilute before because
this is where diluting juice gets its name. The juice
that you buy from the shop is concentrated and you
need to dilute it by adding water before you drink it.
Fizzy juice is also a solution. Carbon dioxide gas is
dissolved in these drinks to make them fizzy.
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Adapted from LCW Booklets
Answer the following questions.
1. Explain why diluting juice is called this.
2. Name the gas used to give fizzy drinks their fizz.
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Adapted from LCW Booklets