This page contains the AQA GCSE Chemistry Using Our Resources Questions and kerboodle answers for revision and understanding The Earth’s Resources .This page also contains the link to the notes and video for the revision of this topic.
Banner 1 C15. 1 Rusting AQA GCSE Chemistry C15 Using Our Resources Kerboodle Answers Page No. 221
1. Answer. Experiment to demonstrate that both air and water are needed for iron to rust.
Take three test tubes A, B, and C and place one clean iron nail in each of them. In the test tube, A pour some water and close its mouth with the help of a cork. In the test tube, B pour boiled water which does not contain dissolved air. Also, pour some oil in test tube B to form a layer over boiled water. The layer of oil will prevent the entry of air in water. In the test tube, C put some anhydrous calcium chloride and cork it. Anhydrous calcium chloride is a drying agent. So, it is added into test tube C to absorb all the moisture present in the air of the test tube. Keep these test tubes undisturbed for some days.
After some days, you will observe that the nail in test tube B does not rust because the nail was exposed only to water and no air was present in it. In the same way, the nail present in test tube C does not rust because in this tube the air is dry and water is not present. But the nail present in test tube A rusts because in test tube A the nail was exposed to both air and water.
This shows that for rusting of iron both air and water are necessary.
2. a. Answer. Rust is chemically hydrated iron oxide. Hydrated iron(III) oxides Fe2O3.xH2O
b.
It is difficult to write a chemical formula of rust as iron show two valencies so it is difficult to predict which oxidation state of iron will be formed.
b. Answer.
Because sometimes it is present in form of iron[II] and sometimes in form of iron[III].
3. a. Answer.
Five ways of preventing iron from rusting are:-
Galvanization
Organic coating
Painting
Applying oil or grease
Sacrificial protection.
b. i. Answer.
Applying oil is the best method to prevent a bicycle chain from rusting because it undergoes high friction and tension.oil also reduces friction.
ii. Answer.
To protect the railings from rusting Galvanization of metal is the best method because if we paint it will go away very quickly because of heating.
iii. Answer.
To prevent a gas pipeline from rusting along the sea bed, Sacrificial protection is required because it comes in contact with water all the time and we have to use a very advanced method for rust control.
4. Answer.
Take two nails one we have to dip in seawater and other in freshwater. After that, we have to make an observation table. We have to take observations.
b. Answer.
By observing the nails we can identify that rusting is faster in seawater because of the presence of salts the cells form easily and rusting is enhanced while in case of freshwater minimum no. of ions are present and formation of a cell is not supported .there is a very high concentration of salts in seawater which supports rusting.
5. Answer.
side given-2.0m
Hence, area-4m2
Total zinc used =zinc per unit area* total area
=300*4 = 1200g
molar mass of zn-65
Banner 2 C 15.2 Useful alloys AQA GCSE Chemistry C15 Using Our Resources Kerboodle Answers: Page No. 223
1. Answer.
Brass is made by alloying copper with zinc. Brass is harder than copper but it is workable. It is ductile and it’s easy to mint coins.
Malleability- It can be hammered into sheets and pressed into intricate shapes.
2. a. Answer.
Because it contains carbon as the impurity it is brittle and breaks on applying pressure on it.
b. Answer.
Wrought iron is an iron alloy with very low carbon content with respect to casting iron. It is soft, ductile, magnetic, and has high elasticity and tensile strength. It can be heated and reheated and worked into various shapes.
Although wrought iron exhibits properties that are not found in other forms of ferrous metal, it lacks the carbon content necessary for hardening through heat treatment. Wrought iron may be welded in the same manner as mild steel, but the presence of oxides or inclusions will provide defective results.
3. Answer.
4. a. Answer.
They are highly corrosion resistive. They do not rust at all. These properties make them ideal for use for making surgical instruments.
b. i. Answer Low carbon steel is used for making car bodies.
ii. Answer High carbon steels used because they are hard and not stretch on heating and pressure.
5. a. Answer.Because of their hardness and light weightiness which are the main needs of an aircraft so its very suitable for making the body of aircraft.
b. Answer.
Gold is highly malleable metal, actually the best malleable metal. Ornaments can’t be made from pure gold because it is very soft and can’t maintain its rigidity.
In order to maintain its rigidity, gold has to be alloyed with copper or silver. Pure gold is very weak and wears away more easily than its alloy with copper. The purity of gold is often expressed in carats. A 24-carat gold is an almost pure gold (99.9%). An 18-carat gold ring will contain (75%) gold. That’s why we have to use alloys rather than pure gold for making rings it gives luster and rigidity to gold.
C 15.3 The properties of polymers AQA GCSE Chemistry C15 Using Our Resources Kerboodle Answers: Page No. 225
1. a. Answer. They are made up of individual polymer chains that are tangled together.
b. i. Answer.
If you heat up a thermosoftening polymer it typically becomes a viscous fluid. They are either glasses or semi-crystalline materials than will melt. Thermosets are typically heavily cross-linked systems. Think of a tangled network. Think a tangled fishnet. They may still undergo a glass transition, but then you go from a hard glassy state to a rubbery state. Not a fluid melt.
The “setting” part of the name refers to what happens when you make them. This is what created all the cross-linking.
ii. Give two differences in the properties of the two types of polymer.
ii. Answer.
The forces between the polymer chains are weak in thermosoftening polymers. These covalent bonds are strong. The covalent ‘cross-links’ between chains do not allow them to separate. These polymers soften quite easily. They will then reset when they cool down. But others do not.
2.
2. Answer.
We use pans in cooking which produces a lot of heat.
If we use thermosoftening polymers then they will melt on heating .so we use thermosetting which doesn’t have any effect on heating.
3.
3. Answer.
Intermolecular forces between monomers of A is more than that of B. A and B are thermosoftening polymers. C is thermosetting because it has no effects on heating.
4. a. Answer.
Reaction conditions are varied to produce two types of polymers.
b. Answer.
High density (HD) Using a catalyst at 50°C and a slightly raised pressure, ethene makes HD poly(ethene). This is made up of straighter poly(ethene) chains. It also has a higher softening temperature and is stronger than LD poly(ethene). They can pack more closely together than branched chains. Low density (LD) poly(ethene). This is made by using very high pressure and traces of oxygen. Polymer chains are randomly branched. So it has a low density. Both are made from ethene monomers, but they are formed under different reaction conditions.
C 15.4 Glass, ceramics, and composition AQA GCSE Chemistry C15 Using Our Resources Kerboodle Answers: Page No. 227
1. a. Answer.
Sand, limestone, sodium carbonate–soda –(Na2CO3) are the raw materials needed for soda-glass and borosilicate glass.
b. i. Answer.
Both soda glass and borosilicate glass are disorderly structured and they both use sand as a raw material.
ii. Answer.
Borosilicate glass melts at more temperature than that of soda lime glass.
2.
2. Answer.
Cob will be considered a Composite because it’s a mixture of different substances.
3.
3. Answer.
when clay fired in a furnace, the water is driven out and strong bonds form between the layers in the giant structure, changing the properties. The higher the temperature inside the furnace, the harder the ceramic formed. Brittleness-because a sharp blow can distort layers in their structure so that ions with like charges are adjacent and repel each other away, cracking the ceramic object.
4. Answer.
Modern composite is a material made from two or more constituent materials with significantly different physical properties that, when combined, produce a material with characteristics different from the individual components. The individual components remain separate and distinct within the finished structure. The new material may be preferred for many reasons: common examples include materials that are stronger, lighter, or less expensive when compared to traditional materials.
Due to its structure which is more even in the case of fiberglass rather than of carbon fiberglass which is harder than fiberglass.
By hitting on fibre glass which does not break by normal hitting but carbon fibre can easily break.
C 15.5 Making Ammonia-The Haber Process AQA GCSE Chemistry C15 Using Our Resources Kerboodle Answers: Page No. 229
1. Answer.
To manufacture ammonia, nitrogen is obtained from the air, hydrogen is obtained mainly from natural gas.
2. a. Answer.
Balanced Equation for the manufacture of ammonia
N2 (g) + 3 H2 (g) → 2 NH3 (g) (ΔH° = −91.8 kJ )
b. Answer.
Nitrogen and hydrogen will react together under these conditions: a high temperature – about 450ºC. a high pressure – about 200 atmospheres (200 times normal pressure) an iron catalyst.
3. a. Answer.
The ammonia is removed by cooling the gases so that the ammonia liquefies.
b. Answer
The unreacted nitrogen and hydrogen gases are recycled back into the reaction mixture.
4.Answer. Flowchart of the Habers Process
5. Answer
Since Haber’s process makes only one desired product, the atom economy of Haber’s process is 100%.
B. Answer
Since the Haber’s process makes only one desired product the atom economy is 100%. All the reactants and the resources are used to make our desired product.
c. Answer.
The production of ammonia via the Haber-Bosch process consumes large amounts of fossil fuels and releases large amounts of greenhouse gases. Ammonia has many important applications including fertilizer for crops and for microalgae-derived biofuel systems. Aquatic cyanobacteria fix nitrogen from the air and have been mass-cultured for many uses. When compared to the ammonia produced via the Haber-Bosch process, savings of about 1.0 × 105 MJ of non-renewable energy and 3100 kg CO2 equivalent of global warming potential per 1000 kg of liquid ammonia might be possible. The results are robust and are not sensitive to the model parameters. The proposed system, if implemented, might have a significant impact on many important global issues such as global warming, fossil fuel depletion, and food security.
C 15.6 The economics of Haber process GCSE Chemistry C15 Using Our Resources Kerboodle Answers: Page No. 229
Page No. 231
1. Answer.
Iron catalyst is used in Haber’s process as It increases the rate of both forward and reverse reaction.
2. a. Answer.
Increasing pressure will increase the yield of ammonia. According to the le chatelier principle, reaction shifts in the forward direction as increasing the pressure will shift the reaction to less gaseous moles side which is the forward side.
b. Answer. Rate of production of ammonia also increases.
3. a. Answer.
30%
b. Answer.
10%
c. Answer.
95%
d. Answer.
82%
e. Answer.
Because it’s not economical to increase the pressure above 200 atm, so the process becomes expensive. providing more temperature also not economical. By balancing pressure and temperature we make it economical.
C15.7 Making fertilizers in lab AQA GCSE Chemistry C15 Using Our Resources Kerboodle Answers Page No. 233
- Equation of fertilizer from ammonia and nitric acid
- Equation of fertilizer from ammonia and sulphuric acid
- Equation of fertilizer from ammonia and phosphoric acid
2. 2D diagram showing titration set up.
3. Answer
b. Answer.
Since the reaction is an acid and base reaction so it is a Neutralisation reaction.
c. Answer.
We can collect pure samples of ammonium sulfate by filtering off by filter paper. Rinse off the remaining material.
It subjects to certain corrections. When the reaction is complete the solution is filtered, evaporated to crystallization.
5. Answer
2NH3 + H2SO4 = (NH4)2SO4
Volume of H2SO4= 15.15 cm3
=0.01515 dm3
Concentration of H2SO4 =0.20 mol dm-3
Moles of H2SO4 = 0.20*0.01515
=0.003 moles
Since there 1:2 ratio of moles of ammonia and sulphuric acid so moles of sulphuric acid = 0.006 moles
V=0.025 dm3
So Concentration = Moles/Volume
=0.006/0.025
=0.24 mol dm3
C 15.8 Making fertilizers in industry AQA GCSE Chemistry C15 Using Our Resources Kerboodle Answers: Page No. 235
1 a (i). Answer. When phosphate rock is treated with nitric acid it forms calcium nitrate.
Ca(NO3)2.
1 a (ii). Answer. When phosphate rock is treated with phosphoric acid it forms calcium phosphate.
Ca3(P04)2.
B (i). Two potassium compounds that are used as fertilizers Potassium chloride–KCl
Potassium sulfate- K2SO4,
(ii). Two compounds that are found in single superphosphate fertilizer
Answer.
Calcium phosphate Ca3(PO4)2
gypsum- CaSO4
2. a. Answer. Ph
Calcium and potassium are found in the phosphate rock.
b. Answer.
The formula of phosphate ion is PO43-
c. Answer.
Ionization of phosphoric acid
H₃PO₄ ==˃ PO₄3-+ 3 H+
3. Answer. Ammonium phosphate is better over ammonium nitrate as ammonium nitrate has
high nitrogen content.
4.
4. Answer.
urea=> NH2-CO-NH2
total mass=60
mass of nitrogen = 14, 2 molecules hence m=28
N%= mass of nitrogen X 100
mass of urea
= 28 X 100
60
N%= 46.6% in urea
N≈14.007 amu
H≈1.0079 amu
S≈32.065 amu
O≈15.999 amu
(NH4)2SO4=2⋅(14.007+4⋅(1.0079))+32.065+4⋅15.999
≈132.1382 amu
So then:
MNM(NH4)2SO4=14.007132.1382≈10.6% of each N atom
→21.2% since it is (NH4)2 and thus there are two N atoms in therein ammonium sulfate.
In ammonium nitrate
%of N-28/80*100=35%
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AQA GCSE Chemistry C15 Using Our Resources Kerboodle Answers Page No 236
- a(i) A shows iron nail in contact with air.
(ii). C shows iron nail in contact with water and air.
(iii). B shows iron nail in contact with only water.
b. Water in tube B is boiled to remove oxygen.
c. Answer.
Nail in tube A is suspended on cotton wool above the anhydrous calcium chloride in the bottom of the tube to keep it away from moisture on calcium chloride.
d. Answer.
The conclusion drawn from this experiment is that both air and water is needed for iron to rust.
e. Answer.
Common salt that is sodium chloride present in seawater makes the cars near to coast more prone to corrosion.
f. Answer
To test which substance makes the nail rust more quickly we can take the nails and keep all the conditions the same and make one test tube exposed to air and water and other test tube exposed to air and sodium chloride solution.
We will use the same volumes of water and sodium chloride solution, leave under the same conditions for a set time, then see which nail forms more rust. We will observe that the iron nail exposed to salt and water will rust more quickly.
g. i. Answer.
We use oil/grease to prevent rusting because cogs constantly rubbing against each other when the machine is working, so coatings wear off quickly.
ii. Answer.
We use a thin coating of tin because it is unreactive tin will not dissolve into any food by reacting with the different foods. e.g., acidic juices.
iii. Answer.
We use sacrificial protection using more reactive metal / attach bars of more reactive metal, as do not need complete covering over iron, cutting cost on difficult repairs needed if the barrier was underground, last a long time before they need replacing.
2. a. Answer.
Polymers don’t have double bonds while alkenes have. Polymers are very long-chained but alkenes are not.
b. i. Answer.
LD-Low density HD-High density
ii.
ii. Answer.
Polymers which melts on heating are thermosoftening as they have weak intermolecular forces between them.
c. i. Answer.
Thermosetting polymers do not melt on heating as they have strong cross-links between them.
ii. Answer.
Thermosetting polymers have long chains cross-linked which are difficult to break so they do not melt on heating. They join together to form large structures. Polymers which melts on heating are thermosoftening as they have weak intermolecular forces between them.
3.
a.i. Answer.
The yield of ammonia increases with an increase in pressure as an increase in pressure will shift the reaction to the less gas moles side. So the reaction will shift towards the right.
ii. Answer.
An increase in temperature decreases the yield of ammonia as the reaction is exothermic. So an increase in temperature will shift the equilibrium to the left.
iii. Answer.
1. pressure: choose one temperature and follow the pattern down a column as pressure increases.
2. temperature: choose one pressure and follow pattern across a row as temperature increases.
b. Answer.
We know that by increasing pressure improves the yield of ammonia and increases the rate of reaction But pressure cannot be raised any higher for economic reasons.
Making a plant to withstand higher pressures costs more.
Generation of higher pressures requires more energy and increased safety risk e.g., explosions at the plant, the temperature cannot be decreased, although this would improve the yield of ammonia, as the rate of reaction too slow. So we use moderate pressure and temperature and use a catalyst to increase the rate of both forward and reverse reactions at the same rate.
c. Answer.
No effect of iron on the yield. The catalyst helps the equilibrium to be attained faster.
4. A. Reaction profile diagram of the reaction with and without the catalyst
b. Answer.
The volume of ammonia per hour = 125 cm3
The volume of ammonia in 24 hours = 125*24
= 3000 cm3
Moles of ammonia = 0.125 moles
Mass of 1 mole of ammonia = 17 g
Mass of 0.125 moles of ammonia = 2.125 g
Mass of ammonia produced in 24 hrs= 2.125 g
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Practice questions AQA GCSE Chemistry C15 Using Our Resources Kerboodle Answers: Page No. 237
1.1 Iron is lower in the reactivity series than carbon. So iron oxide can be displaced by carbon to form iron and carbon dioxide.
01.2. Answer.
In the reaction above the desired product is iron. So the mass of
4 moles of Fe = 224 g
the sum of relative formula masses of all reactants = 356
Percentage atom economy = 224/356*100 = 62.9%
01.3. Answer.
Carbon dioxide is a greenhouse gas and it causes global warming so it is important that the carbon dioxide is not released in the atmosphere.
01.4.Answer.
In pure iron, the layers can slide over one another therefore the metal is malleable and ductile. In steel, iron is mixed with carbon which is of a different sizes than iron. Carbon disrupts the regular arrangement of the layers so they can no longer slide over one another.
01.5. Answer.
Paint acts as a barrier and prevents the reaction of iron with oxygen and water.
01.6. Answer.
Magnesium prevents iron by the method of sacrificial protection. We know that magnesium is more reactive than iron.So it donates electrons or is oxidized or reacts in preference to iron preventing iron from rusting.
02.1.
Answer
02.2.
02.2. Answer. Thermosoftening polymers have weak intermolecular forces between them. So low heat can overcome those forces therefore they melt at a lower temperature. On the other hand, thermosetting polymers have strong cross-linkages between them so they are difficult to melt.
02.3. Answer.
It is so-called because concrete reinforced with metal is a mixture of materials or a mixture of concrete, sand, and gravel, therefore it is a composite.
03.1. Answer.
Reversible reaction.
03.2. Answer.
Equilibrium is a condition when the rate of the forward reaction is equal to the rate of the reverse reaction.
03.3. Answer.
N2(g) + 3 H2 (g) = 2NH3 (g)
The above reaction has less gas moles on the right side. So an increase in pressure will shift the reaction to the less gas moles side according to the Le chatelliers principle so high pressure will give a high yield of ammonia.
The above reaction is also exothermic. So low temperature will shift the reaction to the exothermic side increasing the yield of ammonia.
So to have a high yield of ammonia, high pressure and low temperature are required. But these conditions are not economical. High pressure involves high energy cost and is expensive to set up. On the other hand, low temperature will make the rate of reaction too slow that it will not be economically profitable.
So to have the high yield of ammonia with the high rate we use moderate temperature and pressure and to increase the rate at these conditions iron catalyst is used. Also, the unreacted gases are recycled back to increase the yield.
03.4. Answer.
To form ammonia nitrate ammonia should react with nitric acid.
03.5. Answer.
Formulations are a mixture of two or more compounds to make more useful compounds. NPK contains nitrogen phosphorus and potassium fertilizers. so these are called as formulations.
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