2C

• The rate of reaction can be found by measuring the quantity of reactant used or the quantity of product formed over time. $Rate=$$1/time$
• Factors that affect the rate of reaction are; concentration, surface area, pressure, temperature and catalysts.
• Collision theory explains how various factors affect the rate of reaction. According to this theory, chemical reactions occur only when particles collide with each other and with sufficient energy.
• Increasing the concentration, pressure, surface area or temperature will increase the rate of reaction as it increases the frequency of the collisions. Increasing the temperature also makes the collisions more energetic.
• Increasing the concentration will increase the rate of reaction as there are more particles per unit of volume and so the frequency of collisions will increase.
• Increasing the pressure will increase the rate of reactions as it forces the particles closer together, meaning there are more particles per given unit of volume and so frequency of collisions increases.
• Increasing the surface area of reactants increases the rate of reaction as it increases the number of particles that are exposed and available to react, as a result the frequency of successful collisions increases.
• Increasing the temperature increases the rate of reaction as it increases the kinetic energy of the particles. This increases the frequency of particle collisions, and a greater proportion of collisions will have the energy required to react.
• Catalysts change the rate of chemical reactions but are not used up in the reaction. Different reactions need different catalysts.
• Enzymes act as catalysts in biological systems .
• Catalysts increase the rate of reactions by providing a different pathway for the reaction to take that has a lower activation energy.
• In some chemical reactions, the products of the reactions can react again to produce the original reactants. These are called Reversible reactions.
• When a reversible reaction occurs in an apparatus which prevents the escape of reactants and products, equilibrium is reached when the forward and backward reactions occur at the same rate.
• If a system is at equilibrium and a change is made to any of the conditions, then the system responds to counteract the change.
• The effects of changing conditions on a system at equilibrium can be predicted using the idea known as Le Chatelier's Principle.
• If the concentration of one of the reactants or products is changed, the system is no longer at equilibrium and the concentration of all substances will change until equilibrium is reached again.
• If the pressure increases on an equilibrium, the system will act to favor the side with the smaller number of molecules.
• A catalyst speeds up a reaction without being used up itself
• Crude oil is a finite resource found in rocks. Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud.
• Most compounds in crude oil are hydrocarbons, which are molecules made up of hydrogen and carbon atoms only.
• Most hydrocarbons are called alkanes because they have the general formula CnH2n+2. The first four members of the alkanes are methane, ethane, propane and butane.
• The hydrocarbons in crude oil can be separated into fractions, which contain molecules with similar numbers of carbon atoms, by fractional distillation.
• Many of the fuels we rely on for our daily lives such as petrol, diesel, kerosene, heavy fuel oil and liquified petroleum gases are produced from crude oil.
• Fractional distillation works due to a combination of evaporation and condensation. So the oil is heated and evaporated to then rise up the fractioning column and cool in the process. The fractions have different temperatures, so different hydrocarbons will condense at different levels.
• Materials produced from limited raw materials

  • Metals, glass, building materials, clay ceramics, most plastics
• Amount of separation required for recycling depends on the material and properties required of the final product
• Stages of Life cycle assessment

  • Extracting and processing raw materials
  • Manufacturing and packaging
  • Use and operation during its lifetime
  • Disposal at the end of its useful life including transport and distribution at each stage
• Life Cycle Assessment is not a purely objective process
• Copper can be obtained by displacement using scrap iron or by electrolysis
• Products that can be recycled

  • Metals
• Urban lifestyles and industrial processes produce large amounts of waste water that require treatment before being released into the environment
• Life cycle assessment

  Assessing the environmental impact of products in stages: extracting and processing raw materials, manufacturing and packaging, use and operation during its lifetime, disposal at the end of its useful life including transport and distribution at each stage
• Ways of reducing the use of resources

  Reduction in use, re-use, and recycling of materials by end users reduces the use of limited resources, energy sources, waste, and environmental impacts
• Use of water, resources, energy sources, and production of some wastes can be quantified fairly easily, whereas pollutant effects require value judgments
• Products that can be reused

  • Glass bottles
• Alternative methods of extracting metals

  Phytomining, bioleaching
• Recycling metals

  Melting and recasting or reforming into different products
• Sewage treatment

  Screening, grit removal, sedimentation, anaerobic digestion, aerobic biological treatment
• Phytomining


  Plants grow in soil containing copper. Plants are burned and copper is collected from the ash
• Natural resources, supplemented by agriculture, provide food, timber, clothing, and fuels