MODULE mod7A mod7B mod7C mod7D mod7E mod7F mod7G mod7H mod7I mod7J mod7K mod7L mod8A mod8B mod8C mod8D mod8E mod8F mod8G mod8H mod8I mod8J mod8K mod8L mod9A mod9B mod9C mod9D mod9E mod9F mod9G mod9H mod9I mod9J mod9K mod9L 9ea1
9Ea1 Different properties
Name _____________________________ Class ____________
Your task is to fill in this table to compare the properties of metals and non-metals. You might use the internet, reference books and CD-ROMs to help you.
Property
Metal
Non-metal
Are they solids, liquids or gases at room temperature?
Do they have high or low melting points?
Do they have high or low boiling points?
Do they conduct electricity?
Do they conduct heat?
Are they flexible?
Can they be shaped by hitting them with a hammer? This property is called malleability.
What sound do they make if you hit them?
Are they magnetic?
Are their oxides acids or bases? (Remember an alkali is a soluble base.)
[ literacy, research ]
9Ea2 Properties fact sheet
You are going to find out about one element. It might be a metal or a non-metal. Your teacher will tell you which element to research. You might use the internet, reference books and CD-ROMs to help you.
You will need to answer the following questions. You might then use your information to design a poster about this element.
1 Is it a metal or a non-metal?
2 Is it a solid, a liquid or a gas at room temperature?
3 Does it have a high or a low melting point?
4 What is its melting point?
5 Does it have a high or a low boiling point?
6 What is its boiling point?
7 Does it conduct electricity?
8 Does it conduct heat?
9 Is it flexible?
10 Can it be hammered into shape? This property is known as malleability.
11 What sound does it make if you hit it?
12 Is it magnetic?
13 Does it react with oxygen?
14 If it reacts with oxygen, is the oxide that is formed an acid or a base? Remember that alkalis are soluble bases.
15 How do we get this element?
16 What is this element used for?
9Ea3 What do we use metals for?
The first column shows some uses of different metals. Fill in the names of the metals using names from the Metals list at the bottom of the page.
Each metal is used for a different reason. Draw lines to match up the uses and
the reasons. Some metals are used for more than one thing. Fill in the gaps using words from the Uses list at the bottom of the page.
Metals and their uses
Reasons
________________________
is used to coat cans
because it can be made into foil and it is light.
is used for sweet wrappers.
It is also used for
because it is a good conductor of electricity and can be bent.
is used in electrical cables.
because it does not rust easily.
is used for jewellery.
because it is a metal which is liquid.
is used for drain covers.
because it is shiny, looks good and lasts a long time. It is also a good conductor of electricity.
can be used in thermometers
because it is strong and cheap.
Metals: aluminium copper gold iron mercury tin
Uses: aeroplanes bridges headphone connections water pipes
[ knowledge ]
9Ea4 Materials for cars
There are lots of different parts to a car, and car designers have to choose the right materials for each part. Many parts of a car are made from metals.
- The chassis (pronounced 'shass-ee') of the car is the framework that provides most of the strength of the car's body.
- The body panels are the outer 'shell' of the car. They protect the driver from the wind and weather. Body panels can be made from thin sheets of steel, which is pressed into the correct shape, or can be made from special plastics. Steel body panels can provide some of the strength needed in the overall structure of the car.
- The engine block is made from metal.
- Electrical wiring is needed in a car to control the engine and the lights, wipers and other equipment.
- The headlights need filaments made from metal wires.
The chassis of a TVR sports car. The body of a TVR is made of non-metal materials.
1 Look at each of the five car parts listed above. For each part, say which property of metals is important for that use. Sometimes there may be more than one. Explain your answers.
2 a What are the advantages of a steel body over a plastic body for a car?
b What are the advantages of a plastic body over a steel body?
[ knowledge, literacy ]
9Ea5 Metals with a memory
If you heat a metal it expands, but it does not usually change shape unless it melts. Shape memory alloys (SMAs) are special alloys that change shape when they are heated.
An alloy is a mixture of different metals. A shape memory alloy can be made into a particular shape, and allowed to cool. When it is cool it can be deformed (bent) into a different shape. It will keep this new shape as long as it stays below its 'transformation temperature'. If it is heated to a temperature above its transformation temperature, it will change back into its original shape. The alloy can exert a force when it changes shape.
The first time a shape memory change was observed was in 1932, in an alloy of gold and cadmium. However, the change was very small, and it was not until a much bigger effect was seen in a nickel-titanium alloy in 1962 that people began to do much more research into SMAs, and try to find some uses. Today, the most common SMAs are NiTi alloys, and alloys of copper such as CuZnAl and CuAlNi. NiTi alloys are more expensive, but they can exert bigger forces when they change shape, and they are very resistant to corrosion. Copper SMAs are cheaper and easier to make into the required shapes, but are not as resistant to corrosion.
NiTi alloys can be used in medical applications. One such application is a blood clot filter. A NiTi wire is made in a shape that will stay inside a vein and filter passing blood clots. The wire is cooled, and bent so that it can be inserted easily into the vein. When it gets inside the body, heat from the body makes it change back to its original shape.
CuZnAl SMAs can be used in fire safety valves, where the SMA changes shape
and cuts off the supply of toxic or flammable gases if a fire occurs. SMAs can also
be heated using an electric current. One application of this is in satellite release
bolts, which have to release a satellite from a rocket at the right point in the
launch sequence.
1 What is a shape memory alloy?
2 a Name two copper based SMAs.
b Which elements does each SMA contain?
3 Nitinol is the name for a nickel-titanium alloy. Make up a brand name for a CuAlNi alloy.
4 What does 'transformation temperature' mean?
5 Why do you think there was not much interest in SMAs until 1962?
6 Describe one medical use of SMAs.
7 Why are NiTi SMAs more suitable than the copper based alloys for medical applications?
8 Why would an SMA have to be heated by an electric current to release a satellite from a rocket?
9 What is the difference between an alloy and a compound?
[ literacy, knowledge ]
9Eb1 Making hydrogen 1
Apparatus
- Conical flask - Water
- Delivery tube and bung - Dilute hydrochloric acid
- Water trough - Zinc metal
- Beehive shelf - Eye protection
- Boiling tube - Splint
- Tube rack
Wear eye protection.
Label the parts of the first diagram using the words in the box.
beehive shelf delivery tube conical flask water trough boiling tube
Method
1 Fill the boiling tube with water and place it over the end of the delivery tube so that it is set up as shown in the drawing.
2 Add the acid to the zinc in the conical flask and push the bung firmly into place.
3 Hold the boiling tube over the end of the delivery tube until it is full of gas.
4 When the tube is full of gas, place a bung in the end and then remove the tube from the trough of water and place it in a rack.
5 Light a splint. Remove the bung from the boiling tube and place the burning splint into the top of the boiling tube.
6 If the gas explodes with a squeaky pop, it is hydrogen.
[ observing ]
9Eb2 Making hydrogen 2
Hydrogen gas does not dissolve in water and is usually collected using this apparatus.
1 Copy the diagram and label the parts.
2 Write the word equation for the reaction which takes place in the flask when the dilute sulphuric acid is added to the zinc metal.
3 Why is the boiling tube filled with water before the reaction is started?
4 When hydrogen burns in oxygen, it reacts explosively to form water. Describe how to test a tube of gas to find out if it is hydrogen.
5 a The sample of gas produced using the apparatus shown above will not be pure hydrogen. What else will be present in the tube of gas?
b Where did this come from?
6 Explain why this method is unsuitable for collecting a soluble gas.
9Eb3 Fizzing metals
1 a Name the metal in this experiment.
b Name the acid in this experiment.
c How can you tell that a reaction is occurring?
d A gas is given off which produces a squeaky pop.
Which gas is it? Choose from the following:
oxygen hydrogen nitrogen
carbon dioxide argon
e If you wanted to collect this gas, which of these sets of apparatus would you use?
f Explain how the apparatus that you have chosen works.
2 The reaction between zinc and hydrochloric acid produces a salt called zinc chloride. If we had used sulphuric acid instead, the salt would be called zinc sulphate. Copy and complete these word equations.
a zinc + hydrochloric acid → _______________ + _______________
b zinc + _______________ → zinc sulphate + _______________
c _______________ + hydrochloric acid → aluminium chloride + _______________
d aluminium + sulphuric acid → _______________ + _______________
3 Some metals are unreactive and will not react with acids. From this list, which metal would you not expect to react with acids?
zinc aluminium magnesium gold calcium
9Eb4 Hydrogen and the great escape!
Imagine that you are the hydrogen in a molecule of hydrochloric acid. Suppose that a piece of zinc metal was added to the hydrochloric acid.
- Would there be a reaction?
- What would this be like?
- What would happen to you?
- Where would you end up?
Produce a piece of creative writing (a story or a poem) which describes what happens to the hydrogen before, during and after the zinc metal is added to the acid.
Hints
1 It might be helpful to write the word equation for the reaction between hydrochloric acid and zinc metal.
2 Remember that hydrogen gas exists as a molecule containing two atoms.
9Eb5 Hydrogen
Hydrogen is the lightest element. It is a gas at room temperature. Hydrogen is made up of molecules formed from two hydrogen atoms joined together. We can represent this as:
Hydrogen gas is not found naturally in the air, but hydrogen atoms are found in more compounds than any other element. These compounds include water (H2O). Water is the most common compound on Earth and is essential for life.
When hydrogen burns in air, it reacts with oxygen and forms water:
hydrogen + oxygen → water
This reaction gives out a large amount of energy. If the reaction is not carefully controlled, the hydrogen and oxygen react explosively. We see this explosion on a small scale when we test a tube of hydrogen gas with a lighted splint.
The reaction between hydrogen and oxygen is used to power rockets and space craft. Hydrogen is now beginning to be used to power buses and cars. Special tanks store the hydrogen gas under pressure in the boot of the car. Great care must be taken when refuelling so that the risk of an explosion is reduced. The vehicles produce no pollution because the only waste product is water vapour!
The hydrogen mixes with oxygen from the air and burns with a 'squeaky pop'. This is the test for hydrogen gas.
1 Hydrogen gas is not found naturally in the air. Why do you think this is?
2 The Head Teacher thinks that the 'squeaky pop' given off when a sample of hydrogen burns is really an explosion and shouldn't be allowed in the lab. What would you say to help the Head Teacher to understand why it is safe to do this test in science lessons?
3 Hydrogen is being used as a fuel in some road vehicles.
a Why must the gas be stored under pressure in the tanks?
b Write a word equation for the reaction that happens when hydrogen is used as a fuel.
c Write a symbol equation for this reaction.
4 Great care must be taken when refuelling a hydrogen-powered vehicle, to make sure that there isn't an explosion.
a What might cause an explosion?
b If you were the driver of a hydrogen-powered vehicle, what precautions would you take when refuelling?
5 The R101 airship was filled with hydrogen gas.
a Why was hydrogen used?
b Why was this dangerous?
9Eb6 What would happen if … ?
For each of the following reactions, predict:
a whether there will be any reaction between the metal and the acid
b how fast that reaction will be
c what the products will be, writing a word and/or symbol equation for each reaction.
Use the table of reactivity to help you.
1 zinc + hydrochloric acid
2 zinc + sulphuric acid
3 magnesium + hydrochloric acid
4 gold + sulphuric acid
5 sodium + hydrochloric acid
6 copper + hydrochloric acid
7 lead + hydrochloric acid
8 iron + sulphuric acid
Reaction with acid
sodium
reacts very vigorously
calcium
magnesium
aluminium
Reactions become more vigorous as
zinc
you go up the table.
iron
|
lead
slow reaction
copper
no reaction
silver
gold
Table of reactivity.
9Ec1 Rocks and acid
Acid rain corrodes rocks that contain carbonates. Your task is to find out which rocks contain carbonates by seeing which ones are affected by acid rain. You should set up a 'control' experiment using water, so that you can check that any reaction is caused by the acid and not just water.
- Samples of rock (e.g. chalk, marble, Cotswold stone, sandstone, granite, slate)
- 'Acid rain' - Eye protection
- Dropping pipettes - Water
- Universal indicator - Petri dishes
1 Select your samples of rock. For each rock type you will need two pieces of the rock which are about the same size.
2 Place the rock samples into labelled Petri dishes.
3 Slowly add 'acid rain' to one piece of rock, drop by drop, until the rock is standing in a small pool of acid.
4 Slowly add water to the second piece of rock, drop by drop in the same way, until the rock is standing in about the same amount of liquid.
5 Record your observations and then place the dishes in a safe place.
6 Examine the rocks at regular intervals during a week and record any differences between the two samples.
7 Collect the results of all the members of your class.
Considering your results/conclusions
1 Did any of your rock samples react with the acid when it was added?
2 Did any of your rock samples react with the water when it was added?
3 Did any of the rocks used by your class react straightaway? If so, which ones?
4 Which rocks reacted later?
5 What does this tell you about the effect of acid rain on different rocks?
6 What does this tell you about the effect of water on different rocks?
7 From your results, which rocks appeared to contain carbonates?
Evaluation
8 If you wanted to build a house out of rock, which of these rocks would you use? Why?
9 Did you carry out a fair test? How could you have improved your method?
[ observing, considering, evaluating ]
9Ec2 Carbonates and acid
Many rocks contain carbonates. This experiment shows how carbonates react with dilute sulphuric acid.
- Copper carbonate powder - Boiling tubes
- Dilute sulphuric acid - Bung
- 100 cm3 beaker - Delivery tube
- Universal indicator paper - Eye protection
- Sodium carbonate powder - Limewater
- Calcium carbonate powder - Dilute nitric acid
- Dilute hydrochloric acid - Forceps
- Spatula
1 Place 10 cm3 of dilute sulphuric acid in a 100 cm3 beaker and measure the pH carefully using a piece of indicator paper. Hold the paper using the forceps.
2 Add a spatula of powdered copper carbonate. Keep away from any spray from the reaction. Record your observations.
3 Add some more copper carbonate and look carefully at the mixture. Keep adding small amounts of copper carbonate until there is no further reaction.
4 Does the test tube get hot?
5 Test the pH of the solution with indicator paper.
6 Repeat your experiment using either a different metal carbonate instead of copper carbonate, or a different dilute acid instead of dilute sulphuric acid.
Recording your results
1 Write down what happened when you added the metal carbonate.
2 Write down the pH at the start and at the end of these experiments.
3 a Did the pH of the liquid change during the reaction?
b What does this tell you about the reaction?
The experiment could be carried out using this apparatus which allows the gas to be bubbled into limewater.
4 If the limewater turns milky, which gas is released during the reaction?
5 Write a word equation for the reaction which has occurred between copper carbonate and dilute sulphuric acid.
6 Predict the names of the products formed for each of the reactions you carried out.
[ observing, considering ]
9Ec3 Calcium carbonate
The hardness of a sample of water can be tested by adding some soap and seeing whether a lather is formed. Soft water lathers easily with soap, hard water does not.
The hardness of a sample of water can be measured by adding small amounts of soap solution to a fixed volume of water, until a stable lather is produced when the two are mixed. The more soap solution required to make the lather, the harder the water sample.
1 Plan and carry out an investigation to compare the hardness of three labelled water samples using this method (you might like to use various bottled waters).
Hardness can be temporary or permanent. Temporary hardness is due to the presence of calcium hydrogencarbonate in the water. This can be removed by boiling the water. Permanent hardness is caused by calcium sulphate and magnesium sulphate and cannot be removed by boiling the water.
2 Plan an experiment to test your sample of water to find out whether the hardness in your samples of water is temporary or permanent. You may be able to carry out your experiment after your teacher has checked your plan.
[ planning, observing, considering ]
9Ec4 Rocky equations!
Calcium carbonate is one of the most common minerals in the Earth's crust. Rocks such as chalk, limestone and marble are all mainly made from calcium carbonate. Calcium carbonate reacts with acids to give off carbon dioxide gas.
Coral and Simon did an experiment with three different types of rock. They added the same amount of hydrochloric acid to three 10 g samples of rock. This is the apparatus that they used:
Here are their results:
Time in seconds
0
10
20
30
40
50
60
70
80
volume of gas in cm3 (Rock A)
19
32
43
56
59
volume of gas in cm3 (Rock B)
volume of gas in cm3 (Rock C)
25
55
1 Plot these results on a piece of graph paper.
Plot all three lines on the same graph. Use axes like this:
2 Which two rocks were carbonates? Explain your answer.
3 How would you test for carbon dioxide gas?
4 One of the rock samples was marble chips and the other was powdered chalk. Suggest which rock was powdered chalk. Explain your answer.
[ knowledge, presenting, considering ]
9Ec5 International chemistry
The following passages have been taken from science textbooks. Read them carefully.
Passage 1
Quand on melange de l'acide sulfurique (H2SO4) avec du cuivre carbonate (CuCO3), le cuivre carbonate commence à pétiller. Il pétille parce que l'un des produits de cette réaction est un gaz qui s'echappe. Ce gaz est du dioxide de carbone, qui est composè de carbone et d'oxygene. On note l'equation de la réaction entre l'acide sulfurique et le cuivre carbonate:
H2SO4 + CuCO3 → CuSO4 + CO2 + H2O
A Quel est le produit de la réaction entre MgCO3 et HCl?
B Quel acide réagirait avec MgCO3 pour produire MgSO4?
Passage 2
Wenn verdünnte Schwefelsäure(H2SO4) Kupferkarbonat (CuCO3) zugefügt wird, beginnt sie zu schäumen. Der Grund ist, dass eines der Reaktionsprodukte ein Gas ist, welches entweicht. Dieses Gas ist Karbondioxyd, welches die Elemente Karbon und Sauerstoff enhält. Wir können die reaction zwischen Schwefelsäure und Kupferkarbonat in der folgenden Gleichung erfassen:
H2SO4 + CuCO4 → CuSO4 + CO2 + H2O
A Was wird in einer Reaktion zwischen MgCO3 und HCl produziert?
B Welche Säure produziert MgSO4 wenn sie mit MgCO3 reagiert?
1 What are the pages from these textbooks about? Summarise their contents in a few sentences.
2 Answer the questions contained in the French textbook.
3 What can you say about the answers to the questions in the German textbook?
4 Think about these textbooks from different countries. What do they teach you about the language of science?
5 Write a scientific sentence which describes the reaction between copper carbonate and sulphuric acid (forming copper sulphate, carbon dioxide and water) so that it could be understood by a person who does not understand or speak any English.
9Ec6 Reactions in symbols
Since atoms in a reaction cannot be destroyed, when we write a symbol equation we need to make sure we have the same number of each type of atom on each side of the equation.
For example, the following equation is not correct: it is unbalanced.
Zn + HCl → ZnCl2 + H2
The formula for zinc chloride is ZnCl2 so we cannot change that. The formula for hydrogen is H2 and we cannot change that. We can only put extra numbers in front of the formulae:
Zn + 2HCl → ZnCl2 + H2
The equation is now balanced.
The formulae for some compounds are given in the table. Note that some atoms are always grouped together. This is shown by brackets. The small number after the brackets shows how many of these groups you have. So (PO4)2 shows that you have two phosphate (PO4) groups - a total of two phosphorus atoms and eight oxygen atoms.
Name
Formula
calcium chloride
CaCl2
magnesium carbonate
MgCO3
sodium chloride
NaCl
calcium phosphate
Ca3(PO4)2
magnesium chloride
MgCl2
sodium ethanoate
CH3COONa
copper carbonate
CuCO3
magnesium nitrate
Mg(NO3)2
NaHCO3
copper nitrate
Cu(NO3)2
magnesium phosphate
Mg3(PO4)2
hydrogencarbonate
copper sulphate
CuSO4
magnesium sulphate
MgSO4
sodium stearate
CH3(CH2)16COONa
ethanoic acid (also called acetic acid)
CH3COOH
nitric acid
HNO3
sodium sulphate
Na2SO4
phosphoric acid
H3PO4
stearic acid
CH3(CH2)16COOH
hydrochloric acid
HCI
sulphuric acid
H2SO4
1 What are the products of the reaction between a metal carbonate and an acid?
2 Use the formulae in the table to help you write balanced symbol equations for the following reactions. For each reaction, give the complete word equation as well as the balanced symbol equation.
a copper carbonate + sulphuric acid
b magnesium carbonate + sulphuric acid
c calcium carbonate + hydrochloric acid
d magnesium carbonate + hydrochloric acid
e copper carbonate + nitric acid
f magnesium carbonate + nitric acid
g sodium hydrogencarbonate + hydrochloric acid
h sodium hydrogencarbonate + sulphuric acid
i magnesium carbonate + phosphoric acid
j sodium hydrogencarbonate + ethanoic acid
k calcium carbonate + phosphoric acid
l sodium hydrogencarbonate + stearic acid
9Ed1 Making a salt - potassium chloride 1
Read the method for making a salt at the bottom of the page. Then answer the questions before carrying out the experiment.
1 What will you use to measure out 25 cm3 of hydrochloric acid?
2 How will you measure out 2 cm3 of dilute potassium hydroxide solution?
3 What do you expect the pH of the solution in the beaker to be at the start of the experiment?
4 What do you think will happen to the pH as more potassium hydroxide is added to the beaker? Why?
5 How much dilute potassium hydroxide do you think you will need to add? Why?
6 Why does the volume of the liquid go down when we heat the evaporating basin?
7 What is the liquid which we are removing? Where does it go?
8 What are the crystals that form when the evaporating basin cools down?
9 Where have the crystals come from?
10 Write a word equation for the reaction which takes place in the beaker.
- Hydrochloric acid - 100 cm3 beaker
- Potassium hydroxide - 50 cm3 measuring cylinder
- Universal indicator - Evaporating basin
paper - Bunsen burner
- 5 cm3 syringe - Tripod
- Heatproof mat - Pipe-clay triangle
- Forceps - Eye protection
1 Put 25 cm3 of dilute hydrochloric acid in a 100 cm3 beaker.
2 Add 2 cm3 of dilute potassium hydroxide solution and stir well.
3 Measure the pH of the mixture using universal indicator paper.
4 Repeat steps 2 and 3 until the mixture is no longer acidic.
5 Pour the mixture into an evaporating basin and heat the mixture gently.
6 When about a third of the liquid is left, place the hot evaporating basin on a heat-proof mat to cool. Do not let it boil dry or the hot crystals will spit out.
7 Examine the crystals of salt formed.
[ knowledge, observing ]
9Ed2 Making a salt - potassium chloride 2
1 Potassium chloride is formed when dilute potassium hydroxide solution is added to dilute hydrochloric acid. Write a word equation for this reaction.
2 Will there be any acid left in the beaker at the end of the neutralisation reaction?
3 There are three methods which can be used to measure the pH of the solution.
a What are they?
b What are the advantages and disadvantages of using each method when making a sample of a salt?
c Which method would you prefer to use in this experiment? Why?
- Hydrochloric acid - Potassium hydroxide
- 250 cm3 conical flask - Forceps
- 50 cm3 measuring cylinder - Burette
or solution or pH probe
1 Carefully measure out 25 cm3 of dilute hydrochloric acid and place it in the conical flask.
2 If you are using indicator solution, add a few drops and record the result. If you are using a pH probe or indicator papers, measure the pH and record it.
3 Set up a burette filled with dilute potassium hydroxide solution.
4 Slowly add 2 cm3 of the dilute potassium hydroxide solution, swirling the beaker gently.
5 Measure the pH of the solution and record the result.
6 Repeat steps 4 and 5 until the acid has all been neutralised.
7 Record the volume of potassium hydroxide solution needed to just neutralise the hydrochloric acid.
4 a If you used a pH probe or indicator paper, you may be able to separate the salt formed from the solution. How would you do this?
b If you used indicator solution, why would it be difficult to separate pure salt from the mixture?
9Ed3 Salts
Many different salts have been mentioned in this Unit.
1 a For each of the salts listed below, work out what the name shows about the chemicals which reacted together to form it.
Name of salt
What the name shows
zinc chloride
zinc sulphate
copper chloride
potassium chloride
potassium nitrate
b You may also have met the following salts. What do their names show?
iron chloride
calcium sulphate
calcium nitrate
sodium nitrate
aluminium nitrate
silver nitrate
2 Research and write a report on the uses of one of the following salts:
sodium stearate calcium phosphate
potassium nitrate magnesium sulphate
copper sulphate silver nitrate
Use CD-ROMs, the internet and the library to help you in your research.
[ knowledge, research ]
9Ed4 Making salts - the challenge!
COPPER SULPHATE
COPPER NITRATE
MAGNESIUM SULPHATE
ZINC NITRATE
THIS SHOULD BE A DOUBLE SIDED PHOTOCOPY
SALT
Corrosive - causes burns. Dangerous with many metals. Wear eye protection.
Corrosive - causes severe burns. Dangerous with many metals. Wear eye protection.
Highly flammable. Reacts with acids to produce extremely flammable gas. Wear eye protection.
ZINC
Flammable. Dangerous with acids and alkalis. Reacts with water to release flammable hydrogen gas.
copper oxide
Harmful if swallowed. Dust irritates lungs and eyes. Wear eye protection.
magnesium oxide
Non-hazardous (unless swallowed in large quantities). Wear eye protection.
zinc oxide
zinc carbonate
ACID
METAL
METAL COMPOUND
9Ed5 Making salts - mix and match
1 Choose the jigsaw pieces for an acid and an alkali. Write down the names of the two chemicals you have chosen. Now rearrange the pieces carefully, so that you make a salt and water.
Notes
Hydrochloric acid is hydrogen chloride. Nitric acid is hydrogen nitrate. Sulphuric acid is hydrogen sulphate. Water is hydrogen hydroxide.
Some compounds need more than two jigsaw pieces. For example, calcium hydroxide needs one calcium piece attached to two hydroxide pieces.
2 Write down the name of the salt you have made.
3 Now try another acid and alkali. Predict what you think will be formed.
[ revision ]
---------------------------------------------------------------------------------------------------------
9Ed6 Word equations for making salts
A salt is formed when an acid reacts with an alkali. The first part of the name of the salt comes from the name of the metal in the alkali. The second part of the name comes from the name of the acid.
For example, when potassium sulphate is made:
The potassium comes from the potassium hydroxide; the sulphate comes from the sulphuric acid.
The word equation for this reaction is
potassium hydroxide + sulphuric acid → potassium sulphate + water
Different acids form different salts.
chlorides are made from hydrochloric acid
sulphates are made from sulphuric acid
nitrates are made from nitric acid
Use the table to help you write word equations like the one above for the following reactions:
1 Potassium hydroxide reacting with sulphuric acid.
________ ________ + ________ ________ → ________ ________ + ________
2 Potassium hydroxide reacting with nitric acid.
3 Potassium hydroxide reacting with hydrochloric acid.
4 Calcium hydroxide reacting with hydrochloric acid.
5 Magnesium oxide reacting with hydrochloric acid.
6 Calcium hydroxide reacting with sulphuric acid.
9Ed7 Using salts
Salts are very useful chemicals. There are a large number of different salts which have many different uses.
Look at these labels torn off packets and use the information to answer the
questions below.
1 Name two ways that potassium nitrate can be used.
2 Name three elements that plants need for healthy growth.
3 a Write down two uses for copper sulphate.
b Copper sulphate can be made using a reaction between copper oxide and an acid. Which acid?
c Write a word equation for this reaction.
4 a Give two reasons for adding sodium chloride (common salt) to food.
b Suggest an acid and an alkali that could be reacted together to make sodium chloride.
d What is this sort of reaction called?
e What pH is a solution of sodium chloride in pure water?
5 When photographic film is exposed to light, the salt on the film breaks down. What metal do you think is formed?
9Ed8 Making copper sulphate
Copper sulphate is an example of a salt which is formed when an insoluble base reacts with an acid. This is a set of instructions for preparing copper sulphate (CuSO4) from sulphuric acid and copper oxide.
- Add small amounts of solid copper oxide powder to 25 cm3 of dilute sulphuric acid, and stir.
- Keep adding powder slowly until some unreacted copper oxide remains at the bottom.
- Filter the solution to remove the unreacted copper oxide and transfer the filtrate into an evaporating basin.
- Heat the contents of the evaporating basin gently until about a third of the water has evaporated.
- Leave the solution to cool and then examine the crystals which are formed.
1 Write a list of all the apparatus that would be needed to prepare copper sulphate crystals.
2 What safety precautions would you need to take if you were following these instructions?
3 Why was copper oxide added until some was left on the bottom of the beaker?
4 Why is it better to have copper oxide powder left in the beaker after the reaction, rather than having dilute sulphuric acid left behind?
5 Why was it necessary to filter the mixture before evaporating it?
6 Write word and symbol equations for the reaction that took place.
7 What would the copper sulphate crystals look like?
9E Summary Sheets
Reactions of metals and metal compounds
The properties of a substance are the words that we use to describe it, or measurements that we can make on it. Metals and non-metals have different properties.
Metals …
Non-metals …
are good conductors of heat and electricity
are poor conductors of heat and electricity (except for carbon in the form of graphite which conducts electricity)
are shiny
are dull
are solids, often with high melting points (except for mercury)
are mostly solids or gases
are found on the left-hand side of the Periodic Table
are found on the right-hand side of the Periodic Table
are sometimes magnetic - three metals are magnetic (iron, cobalt and nickel)
are never magnetic
form basic oxides
form acidic oxides
are rigid when thick and bendy when thin
are brittle
can be hammered into shape
cannot be hammered into shape - the solid ones break
Using metals
Metals and non-metals have different uses because of their different properties.
Aluminium is used for power lines because it is light and it is a good conductor of electricity.
Iron and steel are used for bridges because they are strong and cheap.
Gold is used for jewellery because it does not corrode and looks nice.
Metals and acids
Many metals react with acids. Some unreactive metals will only react very slowly with strong acids, some will not react at all. Some metals are more reactive and explode when added to acid.
When a metal reacts with an acid, hydrogen gas is given off. The reaction also produces a compound called a salt.
There are three main types of salt:
Chlorides are made when hydrochloric acid is used.
Sulphates are made when sulphuric acid is used.
Nitrates are made when nitric acid is used.
The general equation is:
acid + metal → salt + hydrogen
For example:
hydrochloric acid + zinc → zinc chloride + hydrogen
We can test for hydrogen by putting a burning splint into a test tube of gas. If hydrogen is present, it will explode with a squeaky 'pop'.
Bases
Bases are compounds which react with acids. All metal oxides, metal hydroxides and metal carbonates are bases. Bases which dissolve in water are called alkalis (e.g. sodium hydroxide).
Metal oxides and hydroxides and acids
A metal oxide or a metal hydroxide reacts with an acid to form water and a salt. This reaction is called neutralisation.
acid + metal oxide → salt + water
(or hydroxide)
hydrochloric acid + potassium hydroxide → potassium chloride + water
sulphuric acid + copper oxide → copper sulphate + water
We can check to see if neutralisation has occurred using universal indicator. The pH of the solution gets closer to neutral (pH7).
Metal carbonates and acids
A metal carbonate will also neutralise an acid. This time the products are a salt, carbon dioxide and water.
acid + metal carbonate → salt + carbon dioxide + water
sulphuric acid + copper carbonate → copper sulphate + carbon dioxide + water
We can test for carbon dioxide using limewater. Limewater goes milky if carbon dioxide is bubbled through it.
Some rocks, like limestone, contain calcium carbonate. The rock fizzes when an acid is added and some of the rock is worn away. The rock is weathered.
9E Target Sheet
Topic
Targets
Before the unit
I have learned this
I have revised this
9Ea
1
Know how good metals and non-metals are at conducting heat and electricity.
2
Know which metals are magnetic.
3
Know some of the other properties of metals and non-metals.
4
Know that different metals have different uses because of their properties.
9Eb
Know what happens when metals and acids react.
Know how to test for hydrogen safely.
Know how to write a general word equation for the reaction between a metal and an acid.
Know how to predict the name of the product formed when a metal and an acid react.
9Ec
Know what happens when rocks and acids react.
Know how to test for carbon dioxide.
Know how to write a word equation for the reaction between an acid and a metal carbonate.
Know how to tell if a chemical reaction has taken place.
9Ed
Know what neutralisation is.
Know the general word equation for the reaction between an acid and a base.
Know how to write a word equation for the reaction between an acid and a metal oxide.
Know that there are many different salts and know some of their uses.
9E Word Sheets
Word sheets that include new words from the 'Focus on:' pages are available on the Exploring Science website.
9Ea - Spot the difference
Word
Pronunciation
Meaning
metals
Elements that are shiny, conduct heat and electricity well and often have high melting and boiling points.
non-metals
Elements that are not shiny, and do not conduct heat and electricity well. They often have low melting and boiling points. The solid ones are brittle.
property
Something that is used to describe how a material behaves and what it is like. Hardness is a property of some solids.
9Eb - Metallic fizz
salts
Compounds made in some reactions involving acids. They have a metal part and a non-metal part. The non-metal part is usually chloride, sulphate or nitrate (e.g. potassium sulphate).
9Ec - More bubbles
weathered
Broken down by chemical or physical changes.
9Ed - Metal oxides and acids/All about salts
base
A chemical which reacts with an acid to form a salt.
neutralisation
Mixing an acid and a base together to make a solution with a pH of 7.