OCR Chemistry Module C2 ROCKS AND MINERALS
C2 – Fundamental chemical concepts
Word equations
Symbol equations
Formula with brackets
Formulas – recall
Molecular formula
Displayed formula
Atom – nucleus
Electrons
Ionic bond
Covalent bond
C2a Paints and Pigments
Paint
Pigment
Binding medium
Solvent
Colloid
Colloid – not separate
Oil paint
Emulsion paint
Dyes
Thermochromic paints
Phosphorescent pigments
C2b Construction materials
Metal
Rocks
Rock – hardness
Rock – hardness cause
Man-made
Concrete
Reinforced concrete
Environmental problems
Limestone/marble
Thermal decomposition
Limestone – thermal decomposition
C2c Does the Earth Move?
Structure of the Earth
Crust
Mantle
Mantle – flow
Tectonic plates
Lithosphere
Plate Tectonics – theory
in terms of reactant and products
balanced symbol equations using formulae (some or all with brackets) of the reactants and products
state number/type of atoms in the formula
CO2; CO; H20; 02; CH4; C2H6 (ethane): CaCO3; CaCl2; MgCl2; HCl acid
involving a shared pair of electrons
shows both the atoms and the covalent bonds in a molecule
positive (protons)
negative
between a positive ion and a negative ion
involving a shared pair of electrons
mixture called a colloid; solvent, binding medium and pigment
coloured substance that is used in paint
liquid that carries the pigment; turns to solid and binds pigments to surface
keeps binding medium/pigment runny/liquid
paint particles are mixed and dispersed with particles of a liquid but are not dissolved
components will not separate because particles are scattered or dispersed throughout the mixture and are
sufficiently small they will not settle at the bottom
pigment dispersed in an oil; solvent that dissolves oil; drying of oil paints – oxidation of oil by atmospheric oxygen
water based; dries when the solvent (water) evaporates
colour fabrics; natural; synthetic (increases colours available)
change colour – heated/cooled; warming cup; electric kettles; added to acrylic paints (more colour changes)
glow in the dark; absorb/store energy – released as light over time; safer than radioactive substances
aluminium; iron; from ores
granite; limestone; marble
granite harder than marble; marble harder than limestone
limestone (sedimentary); marble (metamorphic – high pressures/temperatures on limestone); granite (igneous)
brick (clay); cement (limestone/clay heated together); glass (sand): concrete
made when cement, sand or gravel and water are mixed together and allowed to set
composite material – concrete sets around a steel support; combines hardness of concrete and strength of steel
removing rocks; landscape destroyed; reconstructed when the mining or quarrying finished; quarries/mines take
up land-space; increased noise, traffic and dust
calcium carbonate CaCO3
chemical reaction – when heated one substance is chemically changed into at least two new substances
calcium carbonate  calcium oxide + carbon dioxide; CaCO3  CaO + CO2
Living near a volcano
Predicting eruptions
a sphere with a thin rocky crust, mantle and core (contains iron)
thin outer layer of solid rock; rigid
zone between the crust and core
relatively cold and rigid just below the crust but hot and non-rigid – so able to flow at greater depths
movement results in volcanic activity and earthquakes
crust/upper mantle; outer layer of Earth – oceanic plates (under oceans) continental plates (forming continents)
energy transfer – convection currents in mantle causes plates to move slowly; oceanic plates more dense than
continental plates;
collision – oceanic/continental plate  subduction and partial remelting (oceanic goes underneath continental)
Africa/South America – jigsaw fit of continents; matching fossils/rocks
molten rock beneath the surface of the Earth; magma from mantle less dense than crust
crystals from cooling molten rock
molten rock that erupts from a volcano
iron-rich basalt and its coarse equivalent gabbro; runny and fairly safe
silica-rich rhyolite and its coarse equivalent granite; explosive; pumice/volcanic ash and lava ‘bombs’, sometimes
with graded bedding (bigger lumps at the bottom; smaller fragments at the top)
some people choose to live near volcanoes because volcanic soil is very fertile
geologists study volcanoes to predict future eruptions (not 100% certainty); information about Earth’s structure
C2d Metals and Alloys
Copper
Copper – purification
Alloy
Alloys – examples
Alloys – uses
Alloy properties
Smart alloys
extracted by heating its ore with carbon; can be purified by electrolysis; recycling is cheaper/saves resources
electrolysis; impure copper as anode; pure copper as cathode; copper (II) sulphate solution as electrolyte
mixture of two elements one of which is a metal
brass (copper/zinc); bronze (copper/tin); solder (lead/tin), steel, and amalgam (mercury)
amalgam (tooth fillings); brass (musical instruments, screws); solder (soldering!)
different from metals from which it is made; properties may make the alloy more useful than the pure metal
shape memory (go back to original shape after bent) e.g. nitinol (nickel and titanium) – used for specs frames
C2e Cars for Scrap
Iron/aluminium – differences
Iron/aluminium – similarities
Car body – aluminium
Iron/steel
Corrosion – iron
Corrosion – aluminium
Building cars
Recycling
Recycling – laws
iron more dense than aluminium; iron is magnetic, aluminium is not; iron corrodes easily aluminium does not;
iron and aluminium are both malleable; iron and aluminium are both good electrical conductors
lighter (better fuel economy); will corrode less (longer lifetime); more expensive
alloy more useful than pure metal: steel is harder/stronger than iron; steel less likely to corrode than iron
water/oxygen; speeded by salt/acid rain; oxidation reaction; iron + oxygen + water  hydrated iron (III) oxide
does not corrode in moist conditions – protective layer of aluminium oxide which does not flake off the surface
steel, copper and aluminium; glass, plastics and fibres
saves natural resources; reduces disposal problems;
new laws specify minimum % of all materials used to manufacture cars must be recyclable
Subduction
Theory – development
Magma
Igneous rock
Lava
Lava – runny
Lava – sticky
C2f Clean Air
Air – composition
Carbon cycle
Pollutants
Carbon monoxide
Oxides of nitrogen
Sulfur dioxide – acid rain
Catalytic converter
Atmosphere – origin
C2g Faster or Slower (1) + (2)
Chemical reactions
Explosions – dangers
Reaction time/rate
Collisions – frequency
Collisions – energy
Rate – changed by
Temperature
Concentration (pressure for gases)
Particle size (surface area)
Catalyst
Graphs – interpretation
Graphs – calculate
Graphs – additions to
Product/reactant
21% oxygen; 78% nitrogen; 0.035% carbon dioxide
photosynthesis (increases O2/decreases CO2); respiration/combustion (decreases O2/increases CO2)
Carbon monoxide (CO); Oxides of nitrogen (NOx); sulfur dioxide (SO2)
poisonous gas; incomplete combustion of petrol or diesel in car engine
photochemical smog and acid rain; formed in the internal combustion engine
kill plants/aquatic life, erode stonework and corrode metals; formed when sulfur impurities in fossil fuels burn
removes carbon monoxide from the exhaust gases of a motor car; converts CO to CO2;
2CO + 2NO  N2 + 2CO2
gases escaped from interior of Earth (degassing from crust); first atmosphere – ammonia/carbon dioxide;
formation of water; development of photosynthetic organisms increases % of oxygen (until today’s level);
increase nitrogen levels (action of bacteria); lack of reactivity of nitrogen
slow (rusting); fast (burning/explosions – large volume of gaseous products
fine combustible powders in factories (e.g. custard powder, flour or sulfur
shortest reaction time and hence the fastest reaction (fastest rate)
reaction when particles collide; more frequent collisions  faster reaction;
energy transferred during the collision (whether the collision is successful or effective).
temperature; concentration (pressure in gases); particle size (surface area of solid); catalyst
increases temperature  particles move faster (have more energy); more effective/successful/energetic collisions
particles are more crowded; increasing the frequency of collisions between particles
rate increased by using powdered reactant rather than lump; powder has larger surface area; reacts faster
because there are more frequent collisions
substance which changes rate of reaction; unchanged at the end of reaction; specific to particular reaction
reaction finished (graph first horizontal; reactant used up); reaction fastest (steepest)
rate of reaction from the slope of graph
show the effect of changing temperature or concentration on: rate of reaction; amount of product formed
amount of product formed depends on the amount of reactant used