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Knox Academy
Science Department
S2 Science
Our Material World
Part 4
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1
1 Properties of Gases
Learning Outcomes:
• Know what is meant by the property of a substance
• Know how to prepare and test for hydrogen
The properties of a substance tells us about the
Chemical or Physical nature of the substance. For
example the boiling point of natural gas is –162oC.
Boiling point temperature is a property.
Properties of Chlorine:
Activity:
Read the paragraph on p 1 and complete the table
below:
State at room temperature
Colour
Smell
Melting point (oC)
Boiling point (oC)
Solubility
2
Activity:
Complete the following table:
Properties of Hydrogen:
Property
Observation
State
Colour
Effect of lighted splint
Heavier or lighter than air.
Activity:
You will now follow the instructions on p 3 to collect
some hydrogen gas and test it.
Collecting a Gas over Water:
Complete:
Hydrogen is l _ _ _ _ _ _ than air.
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2 Testing Gases
•Practise the Technique of Collecting a Gas
•Use chemical techniques to identify the gas
•Be able to state the test for oxygen, nitrogen and
carbon dioxide
Oxygen, Nitrogen and Carbon dioxide:
Activity:
Watch the demonstration then following the
instructions on page 4 and 5
Complete the following table:
Property
Oxygen
Nitrogen
Carbon
dioxide
Colour
Smell
Limewater test
Burning splint
Glowing splint
Fill in the missing words.
C _ _ _ _ _ d _ _ _ _ _ _ puts out a burning splint and
has an effect on l _ _ _ water.
O _ _ _ _ _ relit a glowing s _ _ _ _ _.
The best way to identify oxygen gas is that it will
R _ _ _ _ _ _ a g _ _ _ _ _ _ splint.
The best way to identify carbon dioxide gas is that it
will turn limewater c _ _ _ _ _.
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3 Identifying an Unknown Gas
•Gain Experience in collecting and identifying gases
The following summarises the information in lesson 2:
Use the words from the word bank on page 6 to
complete.
Three common gases found in air are oxygen, nitrogen
and carbon dioxide. All three gases are
c _ _ _ _ _ _ _ _ and have no smell so we need
chemical tests to identify them.
The glowing splint test involves lighting a splint and
then b _ _ _ _ _ _ it out and putting the g _ _ _ _ _ _
splint into the test tube of gas to see if it
r _ _ _ _ _ _ _. If it does the gas is o _ _ _ _ _ .
The l _ _ _ water test involves shaking the gas in a
test tube with a little limewater and looking for the
limewater to go from clear and colourless to
c _ _ _ _ _. If it does the gas is c _ _ _ _ _
d _ _ _ _ _ _.
As we have just described there are good tests for
o _ _ _ _ _ and c _ _ _ _ _ but not for n _ _ _ _ _ _ _.
Nitrogen is usually identified by the fact that it will
put out a b _ _ _ _ _ _ splint but does not turn l _ _ _
water cloudy.
5
Activity:
Now that you know about gases try to identify gases A
to D. (p7)
Identifying an Unknown Gas
Complete the table
Gas Jar
A
B
C
D
Glowing Splint
Limewater
6
Name of Gas
4 Preparing and Collecting a Gas
•Use a chemical reaction between hydrogen peroxide
and manganese oxide to prepare a gas
•Identify the gas prepared
Activity:
You are now going to collect a gas and find out what
it is.
A Very Important Gas
Test
Tube
Delivery
Tube
Test
Tube
Hydrogen
peroxide
Water
Manganese(IV) oxide
You will collect a gas then test it to find which of
the 3 gases oxygen, carbon dioxide or nitrogen has
been produced.
The limewater test showed that the gas was/ was
not c _ _ _ _ _ d _ _ _ _ _ _.
The glowing splint test showed that the gas was/
was not
o _ _ _ _ _.
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5 Gases in the Air
•Know that air contains
•79% Nitrogen
•20% Oxygen and
•1% other gases
Activity:
Air is a mixture of the gases nitrogen and oxygen you
are going to test some samples to see which one
behaves most like air.
Gas Mixture
Air
100% oxygen
60% oxygen
20% oxygen
Glowing splint test
The mixture which behaved most like ordinary air was
_____ % oxygen.
Air contains _____% oxygen.
Ordinary air does not turn limewater cloudy. However,
limewater does go c _ _ _ _ _ if it is exposed to air for
a few days.
Attach your bar graph of the Gasses in the Air to this
page.
8
6 Trace Gases and Problem Solving
•Know that air contains some very small quantities of
trace gases and what they are
•Know the test for water
•Practise problem solving
Activity:
Water in the air
Cobalt chloride is a convenient test for water.
Cobalt
chloride
paper
Cobalt
chloride
paper
Dry Air
Wet Air
When cobalt chloride paper is in dry air it is coloured
b _ _ _.
When cobalt chloride paper is in wet air it is coloured
p _ _ _.
% Trace Gases in the Air
The percentage of water in the air varies greatly from
place to place and from day to day so water has been
removed from the table on page 13.
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Abundance
The 3 most abundant trace gases in
order are:
1.
a____
2. c _ _ _ _ _ _ _ _ _ _ _ _
3. n _ _ _
Separation of the gases in Air
Use the wordbank on p14
Air is a m _ _ _ _ _ _. To get individual gases air is
first l _ _ _ _ _ _ _ _ by cooling and then it is warmed
up. The separated gases are then r _ _ _ _ _ _ _ _ _ to
make liquid pure gases.
Problem Solving
1.
2.
3.
k______
h_____
h_____
10
7 Burning in Air
 Identify burning as a chemical reaction
 Identify the gas required for combustion
 Observe the effect different oxygen availabilities
have on time of burning.
Activity:
Size of
beaker (ml)
Time the candle burns for (seconds)
Trial 1
Trial 2
Average
Collect a piece of graph paper and draw a line graph of
size of beaker (along the bottom) and average time (up
the side). Staple your graph into your book here.
Experiments are repeated to make sure our results are
_ _ _ _ _.
As the volume of air around the candle increased, the
candle burned for a _ _ _ _ _ _ length of time.
As we increase the volume of air, we increase the
volume of o _ _ _ _ _ gas available for the burning
reaction.
When a candle burns, o _ _ _ _ _ gas from the air is
used up.
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8 Oxygen in Air
• Identify the % of oxygen present in fresh air.
• Identify the % of oxygen present in exhaled air.
• Know the reason why we must repeat an
experiment and calculate an average.
• Plan, carryout and evaluate an investigation.
Activity:
Copy the diagram from page 19.
Complete the following sentences:
When the boiling tube was placed over the burning
candle, the candle burned for a s _ _ _ _ time
before going out.
Water rose _ _ the boiling tube.
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As the candle burned, it used up o _ _ _ _ _ gas
from the air.
Approximately _ _ % of fresh air is oxygen.
Investigation:
Aim:
To find the % of o_ _ _ _ _ in exhaled air.
Hypothesis:
Exhaled air will contain more / less
oxygen than fresh air.
Results:
Type of air
% of oxygen
Trial 2
Trial 1
Average
Fresh
Exhaled
Conclusion:
Fresh air contains approximately _ _ % oxygen.
Exhaled air contains approximately _ _ % oxygen.
Exhaled air contains more / less oxygen than fresh
air.
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9 Burning Carbon
• Identify the gas produced when carbon burns in
air and state its chemical test.
• Investigate the change in mass observed when a
piece of carbon is burned in air.
• State burning is a chemical reaction.
Activity:
Mass (g)
Mass before Heating
Mass after Heating
Change in mass
Complete the following sentences:
The mass of the carbon lump _ _ _ _ _ _ _ _ _ on
heating.
The decrease in mass is due to carbon atoms being
lost as carbon _ _ _ _ _ _ _ molecules.
Carbon dioxide is formed by carbon atoms combining
with _ _ _ _ _ _ atoms from the air.
______+ ______  ______ _______
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Investigation:
Aim: Identify the gas produced when _ _ _ _ _ _ burns
in air.
Hypothesis:
I think that the gas produced when
carbon burns in air is carbon dioxide /
oxygen / nitrogen / hydrogen.
Equipment:
Draw a diagram of your group’s
apparatus.
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Result:
The gas produced by carbon burning in
air is _ _ _ _ _ _ _ _ _ _ _ _ _.
_ _ _ _ _ _ _ _ _ _ _ _ _ causes Lime
Water to change from clear to
_ _ _ _ _ _.
When a material burns _ _ _ substances
are produced. Burning is a chemical
reaction.
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10. Burning Iron
• Identify signs of a chemical reaction
• Investigate the change in mass observed when a
piece of iron is burned in air.
Activity:
Mass (g)
Mass before Heating (can + iron wool)
Mass after Heating (can + iron wool)
Change in mass
As the iron wool was heated the mass
_ _ _ _ _ _ _ _ _.
The iron atoms combined with _ _ _ _ _ _ atoms from
the air to form _ _ _ _ oxide.
The iron _ _ _ _ _ sticks to the surface of the iron
wool.
Iron oxide is a _ _ _ _ _ and has the combined mass of
the _ _ _ _ and _ _ _ _ _ _.
Write a word equation for the reaction you have
observed:
17
11. Fire Fighting
• Identify the three factors required for a fire to
burn.
• Describe how a fire can be extinguished.
• Demonstrate how to extinguish a fire.
• When a material burns it undergoes a chemical
_ _ _ _ _ _ _ _ with oxygen
• If we _ _ _ _ this chemical reaction we are
extinguishing the fire.
• _ _ _ _ fighters use different methods to
extinguish fires.
• Fire fighters extinguish fires by removing _ _ _
factor from the fire triangle.
• The fire triangle shows us the three things that
must be present before a fuel will burn.
______
____
_____
18
Carbon _ _ _ _ _ _ _ gas is produced when calcium
carbonate reacts with the acid.
_ _ _ _ and _ _ _ _ _ _ are removed from the fire
triangle when the fire is extinguished using the fire
extinguisher.
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12. Making Metals
• Give the definition of an ore.
• State that carbon can be used to extract some
metals from their ores.
• Describe how we can extract copper from its ore.
• Describe how we can extract iron from its ore.
Activity: Extracting Copper
HEAT
Complete the following sentences:
 We knew a chemical reaction had occurred due to
the reactants _ _ _ _ _ _ _ _ colour, and _ _ _ _
and _ _ _ _ _ energy were released.
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 _ _ _ _ _ _ metal was extracted from its ore
during the reaction.
 Copper can be used for _ _ _ _ _ _ _ _ _ _ wiring
and _ _ _ water pipes.
 An ore is a compound we can extract a pure
_ _ _ _ _ from.
Extracting Iron:
Collect and complete the diagram of a Blast Furnace.
Staple it into your notes here.
 Limestone is added to the _ _ _ _ _ furnace to
remove impurities found in iron ore.
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13. What makes iron rust?
• Describe rusting as a chemical reaction.
• State the factors required to make an iron object
rust.
• State the methods we may use to prevent an iron
object from rusting.
Activity:
A
water
drying
agent
boiled
water
tube
C
B
oxygen
present?
water
present?
rusting?
A
B
C
• When iron rusts it undergoes a _ _ _ _ _ _ _ _
change.
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• Iron changes from being present as an _ _ _ _ _ _
_ to forming a compound. The chemical name for
rust is
_ _ _ _ _ _ _ _ _.
• A word equation for iron rusting would be:
iron + oxygen  _ _ _ _ _ _ _ _ _
• For iron to rust, _ _ _ _ _and _ _ _ _ _ _ must be
present with the iron.
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14. Speeding up rusting
• State the colour change observed in rust indicator
when rust is present.
• State the relative rates of rusting an iron nail
shows in salt water, distilled water and acid.
• Describe the relative rates of rusting an iron
object will show (a) by the sea and (b) due to
pollution.
Complete the following sentences:
• It can take up to a _ _ _ before we can see visible
signs of an iron object rusting.
• Scientists have developed a special _ _ _ _ _ _ _
_ _ to test for the early stages of rusting.
• _ _ _ _ _ _ (no rust)  dark _ _ _ _ (rust
present)
• The darker the blue colour, the _ _ _ _ _ _ the
speed an iron object is rusting at.
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A
distilled
water
B
C
salty
water
acid
Answer the following questions:
• Which tube(s) showed the most blue colour?
_________
• Which tube(s) showed the most rusting?
__________
• Why should you wash your car more regularly if
you live beside the sea?
_____________________________________
• What effect does the salt spread on the roads
have on the bodies of our cars?
_____________________________________
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• What could cause the presence of acid in the
environment?
_____________________________________
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