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Chemistry (C4 - Chemical Changes (The Reactivity Series (The Series…

- - - - There are oxidation reactions, where electrons are lost.
      - There are reduction reactions, where electrons are gained.
      - Reduction reactions involve the loss of oxygen atoms.
    - - Copper
      - Iron
      - Hydrogen
      - Lead
      - Tin
      - Zinc
      - Carbon
      - Aluminium
      - Magnesium
      - Calcium
      - Sodium
      - Potassuim
  - - - Have the solution of unknown solution in a conical flask.
      - Add a solution of known concentration until it has neutralised the one in the flask (can be seen using an indicator).
      - Using the ratio of volumes required, the concentrations follow the same ratio so can work out the concentration of the unknown solution.
  - - - These liquids or solutions are able to conduct electricity and are called electrolytes.
      - Passing a current through the electrolyte causes the ions to move to the electrodes.
      - Positively charged ions move to the cathode, negative ions move to the anode.
      - This process is called electrolysis.
      - When ionic compounds are melted or dissolved in water, the ions become free to move around.
    - - Cathode
        
        Hydrogen is produced if the metal is more reactive than hydrogen.
        
        Otherwise the metal is always produced here.
      - Anode
        
        Oxygen is produced unless halide ions are present in the solution.
        
        Otherwise the halogen in solution will be discharged at the anode.
    - - Cathode
        
        Always reduction reactions as ions are gaining electrons.
      - Anode
        
        Always oxidation reactions as ions are gaining electrons.
    - - 2H + 2e- ---> H2
      - 4OH- - 4e- ---> O2 + 2H2O
- - - - The amount of reactant is measured either by mass or by volume.
      - The quantity of product can also be shown by the amount of moles produced per unit of time.
      - The rate of a reaction shown on a graph is the gradient of the curve.
      - The rate of a chemical reaction is derived from the amount of product produced in a given time.
    - - Surface area of reactants.
      - Concentration of reactants.
      - Pressure of reacting gases.
      - Temperature the reaction is carried out at.
      - The presence of a catalyst.
  - - - The amount of energy required to initiate a reaction is called the reaction energy.
      - According to the collision theory, reactions only occur when reactants collide with sufficient energy.
    - - Concentration of reactants.
      - Pressure of the reacting gases.
      - Surface area of solid reactants.
  - - - Different reactions need different catalysts.
      - Catalyst change the rate of a chemical reaction but are not used up in the reaction.
  - - - The relative amounts of the reactants and products when equilibrium is reached depends on the conditions that the reaction is occurring in.
      - The effect of changing the conditions of a system at equiliblrium can be predicted by Le Chatelier's principle.
      - Equilibrium can only occur in closed systems and is where the rate of the forward reaction of a reversible reaction equals the rate of the reverse reaction.
    - - Any reversible reaction in a closed system will always tend towards equilibrium. Changing the conditions of the reaction will shift the position of equilibrium to the left or the right of the reaction.
      - Concentration
        
        The same will happen if the concentration of products is decreased.
        
        If the concentration of the reactants increases, more product will be made to reduce the concentration of the reactants (favouring the forwards reaction).
      - Temperature
        
        If the temperature is increased, the relative amounts of products for the endothermic reaction at equilibrium increases. The opposite is true for the exothermic reaction.
        
        If the temperature is decreased, the relative amount of products of the exothermic reaction at equilibrium will be increased. The opposite will be true for the endothermic reaction.
      - Pressure (Mainly for Gases)
        
        If the pressure is increased, the reaction with the least number of moles of products will be favoured.
        
        If The pressure is decreased, the reaction with the most moles of products will be favoured.
- - - - Crude oil is a finite resource found in rocks.
      - It is comprised of ancient biomass (mainly plankton) that was buried in sediment.
      - It is a mix of many compounds called hydrocarbons.
  - - - Crude oil is heated.
      - The fractions all enter the fractional distillation column.
      - As they rise, the gaseous hydrocarbons cool and condense at different rates, so can be separated off from each other.
    - - Lots of solvents, lubricants, polymers and detergents are also products of hydrocarbons.
      - Many fuels we use today are dependant on crude oil.
    - - Boiling Points
        
        BP increases as the hydrocarbon gets larger.
      - Viscosity
        
        Viscosity increases as the hydrocarbon gets larger.
      - Flammability
        
        Flammability decreases as the hydrocarbon gets larger.
  - - - Complete Combustion
        
        Produces CO2 and H2O.
        
        All of the hydrocarbon has been oxidised.
      - Incomplete Combustion
        
        Produces CO, C2 and H2O.
        
        Where there isn't enough oxygen so the hydrocarbon is not completely oxidised.
- - - - Before electrons were discovered, atoms were believed to be just tiny spheres of matter
    - - The nucleus was a ball of positive charge with negative charges embedded into the surface
    - - The nucleus was actually tiny - only 1/10,000th of the atom's diameter - surrounded by electrons (first thought to orbit at random distances) found to be orbiting at specific orbitals / energy levels
- - - - Occurs between a metal and a non-metal. This is because metals form + ions and non-metals form - ions, so there is a force of attraction between them.
      - Ionic substances for giant ionic lattices which have very high melting points. These structures also have a very low electrical conductivity as there are no free electrons to carry the charge.
      - However, when dissolved in water or melted, the individual ions are free to move around - allowing them to carry a charge and thus conduct electricity. This is the foundation principle of electrolysis.
    - - Covalent bonds form solely between non-metals. There are two types of covalent molecules; small covalent molecules and giant covalent molecules.
      - Small covalent molecules have a low melting and boiling point as - although the intramolecular forces are strong - the intermolecular forces are weak, and it is these that are broken in the process of melting or boiling a substance. SCM's are often gases at room temperature (H2) and do not conduct electricity.
      - Giant covalent molecules have very high melting and boiling points as all the atoms are joined together by intramolecular covalent bonds, which are very strong. Also, they are very hard and do not conduct electricity.
    - - Metallic bonds form purely between metal atoms. Each atom 'donates' electrons to the sea of delocalised electrons which causes a force of attraction between all of the metal ions, forming a very strong molecule. Metals have very high melting and boiling points, as well as being malleable in their pure forms due to the uniformity of their structure.
      - The sea of delocalised electrons allows for metals to be great conductors of electricity, as each of the electrons can move freely, carrying a charge flow.
  - - - Solids
        
        Solids have a generally uniform structure in the particle model, with none of the particles being able to move more than jiggle a bit.
        
        Solids are considered uncompressable.
        
        Particles in a solid have a very low internal energy store.
      - Liquids
        
        Particles in a liquid have a slightly higher internal store of energy, and are thus free to move around more as some of the bonds joining them are broken.
        
        Liquid versions of materials take up more room than the solid version - the exception being ice and water.
      - Gas
        
        Gases have a high internal store of energy and are thus completely free to move around. They mover around randomly and take up the most room per unit of mass of any of the states of matter.
      - Plasma
        
        Plasma is essentially ionised gas, where the individual atoms have lost some of their electrons. This results in a mixture of positive ions and negative electrons. If the plasma loses heat, the ions and electrons reform into a gas.
      - Antimatter
        
        Antimatter is a strange substance we don't yet fully understand. However, we know that each subatomic particle of an antimatter atom has the exact same mass as it's normal matter counterpart (or partner), with the opposite electric charge. So an electron is 1- charge, and a positron is 1+.
  - - - Anything that is 1-100nm in size is a nanoparticle
      - Nanoparticles have different properties to the bulk version of the same material as the surface area to volume ratio is so huge.
      - Often, smaller amounts of nanoparticles are needed than bulk materials to be effective.
    - - Fine particles have diameters between 100 and 2500nm
      - Coarse particles are anything between 0.0000025m and 0.00001m.
- - - - Exothermic
        
        Combustion
        
        Oxidation
        
        Neutralisation
      - Endothermic
        
        Thermal Decomposition
        
        Reaction of citric acid with sodium hydrogen carbonate
  - - - Voltage produced by a cell is determined by many factors including the electrodes and the electrolyte.
      - Batteries consist of many cells joined together for a greater voltage.
      - Non-rechargeable have reactions that are not reversible.
      - Cells contain chemicals that react to produce electricity.
    - - Fuel cells are supplied from an external source.
      - Fuel is oxidised electrochemically within the cell to produce a potential difference.
      - Hydrogen fuel cells include the oxidation of hydrogen to produce water and may be an alternative to other fuel cells in the future.