year 8 science
TRANSCRIPT
My last test result
My Target
Name:
Year 8
Science
2
Chemical Reactions Yes maybe No
Level 3
I am able to describe chemical reac-
tions as the rearrangement of atoms
into new substances.
I am able to describe chemical reac-
tions as reactants and products.
Level 4
I am able to describe some general
chemical equations with word equa-
tions.
I am able to describe simple experi-
ments which show some general chemi-
cal reactions.
Level 5
I am able to describe experiments
which show some general chemical re-
actions by symbol equations.
I am able to predict reaction products
based on general equations.
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To be able to describe a chemical reaction as the rearrangement
of atoms.
Lesson 1: What are chemical reactions?
Look at the following word: POST
This word in English means to send by mail. However other
words can be made from the same four letters. These new
words all have different meanings.
What are the other words?
POST ....... ....... ....... .......
....... ....... ....... .......
....... ....... ....... .......
....... ....... ....... .......
Chemical reactions are just like this.
Atoms are rearranged into new substances.
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How do we know a reaction has happened?
Class practical: Is it a reaction?
1. Mix some ink and water.
2. Burn some magnesium. Use a Bunsen to do this.
3. Place 0.5g of zinc powder in a boiling tube and add 30ml of
acid.
What did you see or
feel Was it a reaction?
Mix ink and water
Burn magnesium
Zinc powder and
acid
Can you think of three things which tell us a reaction
has happened?
1. ...................................................................
2. ..................................................................
3. ..................................................................
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Lesson 2: Reactants and products
To be able to describe reactions in terms of reactants and
products.
Every reaction can be written as:
Reactants Products
This shows that a new substance is made form the things
which are reacting.
Class practical: iron and sulphur
Heat carefully
1. Put the REACTANTS into the test
-tube.
2. Heat carefully with a Bunsen burn-
er.
3. Notice what the PRODUCT looks
like.
Mineral wool to
help stop gas
escape.
Test the reactants and the products with a
magnet.
Is there a difference?
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Complete the following by filling in the blanks by using the words in the
list:
products, rearrange, reactants substances.
Chemical reactions ................................... the atoms of the .......................
to make new ................................. These are called the .............................
What did the reactants look like?..........................................................
..........................................................................................................................
What did the product look like?............................................................
.........................................................................................................................
Class activity: Using the molecule kits, make models to show the
following reaction.
CH4 + O2 CO2 + H2O
Draw in a molecule diagram of the reaction equation below:
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To know that in all chemical reactions the number of atoms
stays the same.
Lesson 3: Reactants equal products
Teacher demonstration: lead nitrate and potas-
sium iodide
Method:
1. Put the reactants in a jar.
2. Record the mass of the reactants
3. Shake the reactants
4. Watch what happens
5. Record the mass of the products.
All reactions have the same number of atoms at the end as at the start.
When an equation shows this, it is said to be balanced.
Look at the reaction below. There are two hydrogen atoms on the right
but only one on the left.......what about the other atoms?
Balance this by using the models. Write the correct equation in the
space below.
................ + .................. .................... + ...................
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Class practical: Reaction between Magnesium and Oxygen.
Method:
1. Record the mass of the Mg and bottle tops.
2. Place Mg inside the two bottle tops
3. Heat a lot!
4. Record the mass of bottle tops and products.
5. Subtract mass of bottle tops and products
from mass of bottle tops and magnesium.
What do you notice about the mass of the products compared
to the mass of the starting magnesium?
Can you explain what has happened?
.....................................................................................................................
......................................................................................................................
When a metal reacts with oxygen a METAL OXIDE is formed.
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Lesson 4: Reactions and heat
Class practical: Reaction between zinc (Zn) and copper sulphate (CuSO4)
Method:
1. Place 40ml of CuSO4 solution into the paper coffee cup
beaker.
2. Place the cup into a glass beaker.
3. Place a thermometer through the hole in the top of the paper
cup and record the temperature of the copper sulphate solution.
4. Take the top off the paper cup and add 1g of Zn powder.
5. Replace the top and the thermometer.
6. Record the highest temperature.
Some reactions release heat and some reactions take in
heat
Reactions which release heat
are called: EXOTHERMIC
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Class practical: Reaction between lemon juice and baking soda
Method:
1. Place 40ml of lemon juice into a paper cup
2. Place a thermometer through the hole in the top of the paper
cup and record the temperature of the lemon juice.
4. Take the top off the paper cup and add 1g of baking soda
5. Replace the top and the thermometer.
6. Record the lowest temperature.
Reactions which take in heat are called: ENDOTHERMIC
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Lesson 5: Reactions and gas
Class practical: Chemical reactions and gas.
Method:
1. Assemble the apparatus as shown in the
diagram below.
2. Place 1 g of Mg into the conical flask.
3. pour 40ml of HCl into the flask.
4. Replace the top on the flask.
What was the gas produced?
.....................................................................................
How can we identify the gas?
....................................................................................
To be able to describe gas forming reactions
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Teacher demonstration: magnesium and steam.
Watch the demonstration and the label the diagram be-
low.
Write the word equation for the above reaction.
............ + ............... ............... + ...............
Write the symbol equation of the reaction above.
............ + ............... ............... + ...............
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Class practical: Extraction of metal from metal oxide
Method:
1. Place 1 g of copper oxide into a boiling tube.
2. Add 0.5g of carbon.
3. Heat a lot.
The mixture needs to glow red hot. When this happens remove
from the heat. Empty the contents onto your heat mat.
Lesson 6: Useful reactions - getting metal
What colour are the products? ................................
What do you think you have made? ..............................
Watch the demonstration.
What colour does the
limewater go?
.............................................
What does this tell you?
..............................................
To know and describe combustion as a useful reaction
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Class demonstration: The thermite reaction.
This is the reaction between aluminium and iron oxide.
What is the thermite reaction used for?
Research this and write your answer here:
..................................................................................................................................
..................................................................................................................................
.................................................................................................................................
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Lesson 7: Salt forming reactions
Mg + 2HCl MgCl2 + H2
A salt is a compound where a metal has replaced the hydrogen in an
acid.
Mg + H2SO4 MgSO4 + H2
What are the above acids called?
1. ..............................
2. .............................
3. ..............................
To know what a salt is and to be able to name them
2Na + 2HNO3 2NaNO3 + H2
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Naming salts:
1. The name of the salt has two parts.
2. The first part is always the name of the metal used.
3. The second part is named after the acid used.
HCL gives CHLORIDES
H2SO4 gives SULPHATES
HNO3 gives NITRATES
When you react magnesium and hydrochloric acid you make the salt:
Magnesium chloride
Metal used Acid used Name of salt
Na HCl
Mg HCl
Ca H2SO4
Li H2SO4
Cu HNO3
K HNO3
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Class practical: Making copper sulphate.
Method:
1. Place 1g of CuO into a beaker.
2. Add 20ml of H2SO4.
3. Heat gently
4. Filter.
5. Heat gently until most of the liquid has
Disappeared.
If in doubt look at the pictures below.
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Lesson 8: Fuels
One of the most important chemical reactions is COMBUSTION.
Class practical: Which is the best fuel?
Method:
1. Take a beaker and put 50ml of tap water in each.
2. Record the starting temperature of the water.
3. Place the beaker on a tripod and gauze.
4. Put a spirit burner below the beaker and ignite.
5. Burn for 60 seconds.
6. Record the end temperature.
7. Repeat for the other three spirit burners.
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Teacher demonstration: Products of combustion
What are the products of combustion?
1. .................................
2. .................................
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Lesson 9: Metals
Class practical: Which is the most reactive?
Method:
1. Place 5 test-tubes in a test-tube rack.
2. Place a different piece of metal in each test-
tube.
3. Add 20ml of acid to each test-tube.
4. Watch what happens.
Can you place metals in order of most reactive to least re-
active?
Most reactive: ......................
......................
......................
......................
......................
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Class practical: Displacement reactions to show reactivity
Method:
1. Set up your spotting tile as shown by your
teacher.
2. Record in the blank spotting tile given here.
3. Use a N if no reaction and a Y if a reaction
has occurred.
Teacher demonstration: Products
of combustion
What is the pink stuff on the nail?
.................................................................
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Homework 1: Is there a reaction?
Q.1 What are the three things which tell us a chemical reaction has
happened?
1. ...................................................
2 ...................................................
3. ..................................................
Q.2 Say if the following are chemical reactions or not by adding a Y for
yes and N for no.
1. An egg frying .........
2. Adding ink to water ...........
3. adding metal to an acid ..........
4. Freezing water ..............
Q.3 Explain why adding salt to water is not a chemical reaction.
.............................................................................................................
.............................................................................................................
.............................................................................................................
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Homework 2: Products and reactants
Q.2 Using the picture and key below write out the formula of the
compound.
............................................................................................
Q.1 Look at the word equation. In the space below write in what the reac-
tants and products are.
Magnesium + Hydrochloric acid Magnesium chloride + Hydrogen
Products:...........................................................................
Reactants: .......................................................................
Q.3 Look at the following model diagram of a reaction. Balance
this reaction so the reactants equal the products.
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Homework 3: Crossword
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Homework 4: Graph
Q.1 Use the axes given here to draw graph of the data
Time
(sec)
Temperature
(oC)
0 13
20 23
40 29
60 31
80 32
100 32
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Homework 5: Useful reactions
Q.1 In the space below, produce a poster showing and describing
why combustion is a really useful chemical reaction. This is to be
written by hand NOT printed from a computer.
Combustion is a reaction
which produces:
1.
2.
3.
This is a useful reaction because:
1.
2.
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