GCSE Chemistry C2 (OCR B712): Chemical Resources

Year 10 revision topics

FUNDAMENTAL CHEMICAL CONCEPTS
  • Understand that in a chemical reaction reactants are changed into products.
  • Recognise the reactants and products in a word equation.
  • Construct word equations given the reactants and products.
  • Recognise the reactants and the products in a symbol equation.
  • Work out the number of elements in a compound given its formula.
  • Work out the number of atoms in a formula with no brackets.
  • Work out the number of each different type of atom in a formula with no brackets.
  • Recognise whether a substance is an element or a compound from its formula.
  • Work out the names of the different elements in a compound given its formula.

  • Recognise whether a particle is an atom, molecule or ion given its formula.
  • Understand that atoms contain smaller particles one of which is a negative electron.

  1. Recall that two types of chemical bond holding atoms together are:
    • ionic bonds
    • covalent bonds
  • Understand that a molecule is made up of more than one atom joined together.
  • Understand that a molecular formula shows the numbers and types of atom in a molecule.
  • Work out the number of atoms in a displayed formula.
  • Work out the names of the different elements in a compound given its displayed formula.
  • Work out the number of each different type of atom in a displayed formula.
  • Construct word equations (not all reactants and products given)
  • Construct balanced symbol equations given the formulae (no brackets) of the reactants and products.
  • Explain why a symbol equation is balanced.
  • Construct balanced symbol equations given the formulae (some or all with brackets) of the reactants and products.(HL)
  • Construct balanced symbol equations given the names of the reactants and products.(HL)
  • Work out the number of atoms in a formula with brackets.
  • Work out the number of each type of different atom in a formula with brackets.
  1. Recall the formula of the following substances:
    • calcium carbonate and calcium oxide
    • carbon dioxide, hydrogen and water
    • sodium chloride and potassium chloride
    • ammonia and nitrogen
    • hydrochloric acid.
  1. Recall the formula of the following substances:(HL)
    • nitric acid and sulfuric acid
    • copper oxide, sodium hydroxide, potassium hydroxide and sodium carbonate
    • potassium sulfate, sodium sulfate and ammonium sulfate
    • calcium chloride, magnesium chloride
    • magnesium sulfate and copper(II) sulfate.
  • Understand that a displayed formula shows both the atoms and the bonds in a molecule.
  • Write the molecular formula of a compound given its displayed formula.
  • Construct balanced equations using displayed formulae.(HL)
  • Understand that positive ions are formed when electrons are lost from atoms.
  • Understand that negative ions are formed when electrons are gained by atoms.
  • Understand that an ionic bond is the attraction between a positive ion and a negative ion.
  • Understand that a covalent bond is a shared pair of electrons.
  • Explain how an ionic bond is formed.(HL)
  • Explain how a covalent bond is formed.(HL)
C2a The structure of the Earth
  • Describe the structure of the Earth as a sphere with a thin rocky crust, a mantle and an iron core.
  • Understand how the movement of tectonic plates results in volcanic activity and earthquakes.
  • Recall that the movement of tectonic plates is very slow (about 2.5cm per year).
  • Understand the timescales involved in the movement of continents.
  1. Recognise that:
    • many theories have been put forward to explain the nature of the Earth's surface
    • Earth scientists accept the theory of plate tectonics.
  • Explain how the size of crystals in an igneous rock is related to the rate of cooling of molten rock
  • Describe magma as molten rock beneath the surface of the Earth and lava as molten rock at the Earth's surface.
  • Recall that some volcanoes erupt runny lava, while some erupt thick lava violently and catastrophically.
  • Research examples of people who live near volcanoes and the reasons why.
  • Explain why some people choose to live near volcanoes.
  • Describe the lithosphere as the (relatively) cold rigid outer part of the Earth that includes the crust and part of the mantle.
  • Describe the lithosphere as made of tectonic plates that are less dense than the mantle below.
  1. Explain the problems associated with studying the structure of the Earth:
    • crust is too thick to drill through
    • the need to use seismic waves produced by earthquakes or man-made explosions.
  1. Explain why the theory of plate tectonics is now widely accepted:
    • it explains a wide range of evidence
    • it has been discussed and tested by a wide range of scientists.
  1. Describe the mantle as the zone between the crust and the core which is(HL):
    • cold and rigid just below the crust
    • hot and non-rigid at greater depths and therefore able to move
  1. Describe the theory of plate tectonics(HL):
    • energy transfer involving convection currents in the semi-rigid mantle causing the plates to move slowly
    • oceanic crust more dense than continental crust
    • collision between oceanic plate and continental plate leads to subduction and partial melting
    • plates cooler at ocean margins so sink and pull plates down
  1. Describe in simple terms the development of the theory of plate tectonics(HL):
    • Wegener's continental drift theory (1914)
    • continental drift theory not accepted by scientists at the time
    • new evidence in 1960s - sea floor spreading
    • theory of plate tectonics slowly accepted by the scientific community as subsequent research has supported the theory.
  • Understand that the type of volcanic eruption depends on the composition of the magma.
  1. Describe different types of igneous rocks that are formed from lava(HL):
    • iron-rich basalt is formed from runny lava from a fairly safe volcanic eruption
    • silica-rich rhyolite is formed from thick lava from an explosive eruption
  1. Explain why geologists study volcanoes:
    • to be able to forecast future eruptions
    • to reveal information about the structure of the Earth
  • Explain why geologists are now able to better forecast volcanic eruptions but not with 100% certainty.(HL)
C2b Construction materials
  1. Recall that some rocks are used in construction of buildings and roads:
    • granite, limestone, marble and aggregates.
  1. Explain why there are environmental problems when rocks are quarried or mined from the ground:
    • landscape destroyed and has to be reconstructed when the mining or quarrying has finished
    • increased noise, traffic and dust
  • Recall that limestone and marble are both forms of calcium carbonate.
  • Recall that limestone thermally decomposes to make calcium oxide and carbon dioxide.
  1. Describe how concrete is made:
    • cement, sand, aggregate and water are mixed together
    • mixture then allowed to set.
  • Describe how concrete can be reinforced using a steel support.
  1. Relate some construction materials to the substances found in the Earth's crust from which they are manufactured:
    • aluminium and iron from ores
    • brick from clay
    • glass from sand.
  • Compare the hardness of limestone, marble and granite.
  1. Explain why granite, marble and limestone have different hardness(HL):
    • limestone is a sedimentary rock
    • marble is a metamorphic rock made by the action of high pressures and temperatures on limestone
    • granite is an igneous rock
  • Construct the word equation for the decomposition of limestone

    calcium carbonate -> calcium oxide + carbon dioxide
  • Construct the balanced symbol equation for the decomposition of limestone (given some formulae):

    CaCO3 → CaO + CO2
  • Describe thermal decomposition as a reaction in which, when heated, one substance is chemically changed into at least two new substances.
  • Construct the balanced symbol equation for the decomposition of limestone (formulae not given)(HL):

    CaCO3 → CaO + CO2
  • Recall that cement is made when limestone and clay are heated together.
  • Recall that reinforced concrete is a composite material.
  1. Explain why reinforced concrete is a better construction material than non-reinforced concrete in terms of (HL):
    • hardness of the concrete
    • flexibility and strength of the steel
C2c Metals and alloys
  • Understand how copper can be extracted by heating its ore with carbon.
  • Describe reduction as the removal of oxygen from a substance.
  • Recall that copper can be purified by electrolysis.
  1. Explain why recycling copper is cheaper than extracting copper from its ore:
    • saves resources
    • uses less energy
  • Recall that alloys are mixtures containing one or more metal elements.
  • Recognise that brass, bronze, solder, steel, and amalgam are alloys.
  1. Recall one important large scale use for each of the following alloys:
    • amalgam used in tooth fillings
    • brass used in musical instruments, coins and door decorations eg door knockers
    • solder used to join electrical wires.
  • Recognise that the properties of an alloy are different from the properties of the metals from which it is made.
  • Interpret data about the properties of metals,including alloys eg hardness, density, boiling point and strength.
  • Suggest properties needed by a metal or alloy for a particular given use.
  • Label the apparatus needed to purify copper by electrolysis.
  • Explain some of the advantages and disadvantages of recycling copper.
  1. Describe the use of electrolysis in the purification of copper (HL):
    • impure copper as anode
    • pure copper as cathode
    • copper(II) sulfate solution as electrolyte
    • cathode gains mass because copper is deposited
    • anode loses mass as copper dissolves
  1. Explain why the electrolytic purification of copper involves both oxidation and reduction (HL):
    • Cu2+ + 2e- → Cu as an example of reduction because electrons are gained
    • Cu - 2e- → Cu2+ as an example of oxidation because electrons are lost.
  1. Recall the main metals in each of the following alloys:
    • amalgam - mercury
    • brass - copper and zinc
    • solder - lead and tin.
  • Explain why metals, including alloys are suited to a given use given appropriate data (no recall expected).
  • Evaluate the suitability of metals for a given use given appropriate data(HL).
  1. Explain how the use of 'smart alloys' such as those with a shape memory property have increased the number of applications of alloys (HL):
    • nitinol (nickel and titanium) used to make spectacle frames as the frames will return to their original shape after bending.
C2d MAKING CARS
  • Recall that rusting needs iron, water and oxygen.
  • Recall that aluminium does not corrode in moist conditions.
  • Describe oxidation as the addition of oxygen or the reaction of a substance with oxygen.
  • Interpret simple data about the rate of corrosion of different metals in different conditions (no recall is expected).
  1. Compare the properties of iron and aluminium:
    • iron is more dense than aluminium
    • iron is magnetic and aluminium is not
    • iron corrodes (rusts) easily and aluminium does not
    • iron and aluminium are both malleable
    • iron and aluminium are both good electrical conductors
  1. Recall the major materials needed to build a car:
    • steel, copper and aluminium
    • glass, plastics and fibres
  1. Describe the advantages of recycling materials:
    • saves natural resources
    • reduces disposal problems.
  • Understand how salt water and acid rain affect rusting.
  • Understand that rusting is an oxidation reaction (iron reacts with oxygen forming an oxide).
  1. Construct the word equation for rusting:
    • iron + oxygen + water → hydrated iron(III) oxide.
  • Explain why aluminium does not corrode in moist conditions.
  • Interpret data about the rate of corrosion of different metals in different conditions (no recall is expected).
  1. Understand that alloys often have properties that are different from the metals they are made from and that these properties may make the alloy more useful than the pure metal
    • steel is harder and stronger than iron
    • steel is less likely to corrode than iron.
  1. Describe advantages and disadvantages of building car bodies from aluminium or from steel:
    • car body of the same car will be lighter with aluminium
    • car body with aluminium will corrode less
    • car body of the same car will be more expensive made from aluminium.
  1. Explain advantages and disadvantages of building car bodies from aluminium or from steel:(HL)
    • get better fuel economy because the car body of the same car will be lighter with aluminium
    • longer lifetime because the car body with aluminium will corrode less.
  • Suggest properties needed by a material for a particular use in a car.
  • Explain why a material used in a car is suited to a particular use given appropriate data (no recall expected)
  • Explain the advantages and disadvantages of recycling the materials used to make cars.
  • Explain why new laws specify that a minimum percentage of all materials used to manufacture cars must be recyclable.
  • Evaluate information on materials used to manufacture cars (no recall expected)(HL).
C2e Chemical Economics
  • Recall that in the Haber process ammonia is made from nitrogen from the air and hydrogen that comes from the cracking of oil fractions or from natural gas.
    1. Describe that the cost of making a new substance depends on:
      • price of energy (gas and electricity)
      • cost of starting materials
      • wages (labour costs)
      • equipment (plant)
      • how quickly the new substance can be made (cost of catalyst).
  • Recognise that is used to represent a reversible reaction.
  • Understand that a reversible reaction proceeds in both directions.
  1. Recall some of the uses of ammonia:
    • manufacture of fertilisers
    • manufacture of nitric acid.
  1. Describe how ammonia is made in the Haber process:
    • nitrogen + hydrogen ammonia
    • iron catalyst
    • high pressure
    • temperature in the region of 450°C
  1. Construct the balanced symbol equation for the manufacture of ammonia in the Haber process (given some or all of the formulae):
    • N2 + 3H2 ⇋ 2NH3
  1. Explain the conditions used in the Haber process (HL):
    • high pressure increases the percentage yield of ammonia
    • high temperature decreases the percentage yield of ammonia
    • high temperature gives a high rate of reaction
    • 450 °C is an optimum temperature to give a fast reaction with a sufficiently high percentage yield
    • catalyst increases the rate of reaction but does not change the percentage yield.
  1. Construct the balanced symbol equation for the manufacture of ammonia in the Haber process (formulae not given) (HL):
    • N2 + 3H2 ⇋ 2NH3
  1. Describe how different factors affect the cost of making a new substance:
    • the higher the pressure the higher the plant cost
    • the higher the temperature the higher the energy cost
    • catalysts reduce costs by increasing the rate of reaction
    • when unreacted starting materials are recycled costs are reduced
    • automation reduces the wages bill
  1. Explain how economic considerations determine the conditions used in the manufacture of chemicals (HL):
    • rate must be high enough to give a sufficient daily yield of product
    • percentage yield must be high enough to give a sufficient daily yield of product
    • a low percentage yield can be accepted if the reaction can be repeated many times with recycled starting materials
    • optimum conditions used that give the lowest cost rather than the fastest reaction or highest percentage yield.
  • Interpret data in tabular and graphical form relating to percentage yield in reversible reactions and changes in conditions (no recall required)(HL).
  • Interpret data about rate, percentage yield and costs for alternative industrial processes (no recall required).
  • Recognise the importance of ammonia in relation to world food production.
C2f Acids and Bases
  • Describe how universal indicator can be used to estimate the pH of a solution.
  • Recall the colour changes with litmus.
  • Recall that an alkali is a soluble base.
  • Understand that an acid can be neutralised by a base or alkali, or vice versa.
  1. Understand that indicators use colour change to show changes in pH, including:
    • sudden or gradual changes
    • colour changes over different pH ranges.
  1. Recall that in neutralisation:
    • acid + base → salt + water.
    • Recall that in solution all acids contain H+ ions.
  • Understand that the pH of an acid is determined by the concentration of H+ ions.
  1. Explain why an acid is neutralised by an alkali in terms of the ions present (HL):
    • acids contain H+
    • alkalis contain OH-
    • neutralisation involves the reaction H+ + OH- ⇋ H2O
  • Explain why metal oxides and metal hydroxides neutralise acids.
  • Recall that carbonates neutralise acids to give water, a salt and carbon dioxide.
  • Construct word equations to show the neutralisation of acids by bases and carbonates (names of the products not given).
  1. Predict the name of the salt produced when a named base or carbonate is neutralised by a laboratory acid:
    • sulfuric acid
    • nitric acid
    • hydrochloric acid
    • phosphoric acid
  1. Construct balanced symbol equations for the neutralisation of acids by bases and carbonates for (HL):
    • sulfuric acid, nitric acid and hydrochloric acid
    • ammonia, potassium hydroxide, sodium hydroxide and copper oxide
    • sodium carbonate and calcium carbonate
C2g Fertilisers and crop yields
  • Recall that fertilisers increase crop yield.
  • Recall that plants absorb minerals through their roots.
  • Describe fertilisers as chemicals that provide plants with essential chemical elements.
  • Recall that nitrogen, phosphorus and potassium are three essential elements needed for plant growth.
  • Recognise the essential elements given the formula of a fertiliser.
  • Understand that the use of fertilisers can be beneficial (increasing food supply) and also cause problems eg death of aquatic organisms (eutrophication).
    1. Identify the apparatus needed to prepare a fertiliser by the neutralisation of an acid with an alkali:
      • burette and measuring cylinder
      • filter funnel.
    • Recall the names of two nitrogenous fertilisers manufactured from ammonia eg:
      • ammonium nitrate
      • ammonium phosphate
      • ammonium sulfate
      • urea
  • Explain why fertilisers must be dissolved in water before they can be absorbed by plants.
  1. Identify arguments for and against the use of fertilisers:
    • world population is rising so need to produce more food
    • eutrophication and pollution of water supplies can result from excessive use of fertilisers.
  1. Explain how the use of fertilisers increases crop yield (HL):
    • replaces essential elements used by a previous crop or provides extra essential elements
    • more nitrogen gets incorporated into plant protein so increased growth.
  1. Explain the process of eutrophication:
    • run-off of fertiliser
    • increase of nitrate or phosphate in river water
    • algal bloom
    • blocks off sunlight to other plants which die
    • aerobic bacteria use up oxygen
    • most living organisms die
  1. Predict the name of the acid and the alkali needed to make a named fertiliser, for example:
    • ammonium nitrate.
  1. Describe the preparation of a named synthetic fertiliser by the reaction of an acid and an alkali (HL):
    • names of reactants
    • experimental method
    • how a neutral solution is obtained
    • how solid fertiliser is obtained
C2h Chemicals from the sea: the chemistry of sodium chloride
  • Recall that sodium chloride (salt) can be obtained from the sea or from salt deposits.
  • Recall that the electrolysis of concentrated sodium chloride gives chlorine and hydrogen.
  • Recall that the chemical test for chlorine is that it bleaches moist litmus paper.
  1. Recall that sodium chloride is used:
    • as a preservative
    • as a flavouring.
  • Understand that sodium chloride is an important raw material in the chemical industry, including use as a source of chlorine and sodium hydroxide.
  • Recall that household bleach, pvc and solvents are made from substances derived from salt.
  • Recall that chlorine is used to sterilise water and to make solvents, household bleach and plastics.
  • Recall that hydrogen is used in the manufacture of margarine.
  • Recall that sodium hydroxide is used to make soap.
  • Describe how salt can also be mined as rock salt and by solution mining in Cheshire.
  • Explain how mining for salt can lead to subsidence.
  1. Recall the products of the electrolysis of concentrated sodium chloride solution (brine):
    • hydrogen made at the cathode
    • chlorine made at the anode
    • sodium hydroxide is also made
  • Explain why it is important to use inert electrodes in the electrolysis of sodium chloride solution.
  1. Explain how the electrolysis of sodium chloride solutio-, H+
  2. cathode 2H+ + 2e- → H2
  3. anode 2Cl- - 2e- → Cl2
  4. ions not discharged make sodium hydroxide.
  • Explain why the electrolysis of sodium chloride involves both reduction and oxidation (HL).
  • Describe how sodium hydroxide and chlorine are used to make household bleach.
  • Explain the economic importance of the chlor-alkali industry (HL).

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