Predicted primrose

• How long ago was Earth formed?

  4.6 billion years ago
• Gases found in the Earth's current atmosphere in small amounts

  -water vapour

  -noble gases

  -methane

  -carbon monoxide

  -ammonia
• Explain why the composition of nitrogen in Earth's atmosphere increased over time

  There was a lot of volcanic activity- volcanoes released nitrogen, which built up
• Why is it difficult to know the exact composition of Earth's early atmosphere?

  limited evidence due to very long (4.6 billion years)time scale
• fuels such as wood(methane)

  undergo complete/incomplete combustion.
• complete combustion of fuel methane

  $CH_4+$$2O_2---->CO_2+$$2H_2O$
• rate of reaction unit

  g/s
• How does concentration affect the rate of reaction

  Increasing concentration increases the rate of reaction
• explain

  -higher concentration=more crowded particles

  -more particles per unit volume

  -More frequent successful collisions

  -more successful collisions per unit time
• hydrogen gas test

  test-burning splint

  result-squeaky pop sound
• reversible reaction symbol

   ⇌
• Le chatlelairs principle

  -When a change is made to a system at equilibrium.

  -The position of equilibrium shifts to counteract the change
• What changes if ice is added to a beaker of hydrated cobalt (ions)

  -stay pink

  -equilibrium shifts to the left-hand side (reactants)

  -as the forward reaction is endothermic backwards reaction would be exothermic.
• Effect of pressure on the position of equilibrium

  No effect-reaction has no gas molecules
• State which property of hydrocarbons makes it possible to separate them by fractional distillation

  Boiling Points
• Why are life cycle assessments (LCAs) used

  to assess and evaluate the environmental impact of different products.
• stages of LCAs

  1. Extracting and processing raw materials
  2. Manufacturing and packaging
  3. Use and operation during its lifetime
  4. disposal
• carbon footprint meaning

  The total amount of carbon dioxide and other greenhouse gases emitted over the life cycle of a product/service
• Why use an independent company to carry out LCA

  to avoid bias
• Potable water

  -low levels of dissolved salts and microbes

  -safe to drink
• Explain the role the evolution of plants had on the composition of oxygen and carbon dioxide in the Earth’s atmosphere.

  [4 marks]

  Any four from:

  • Algae and plants produced oxygen by photosynthesis
  • Algae and plants take in carbon dioxide by photosynthesis
  • Carbon dioxide + water → glucose + oxygen(6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂)
  • Oxygen first appeared in the atmosphere due to algae (about 2.7 billion years ago)
  • As plants evolved, more oxygen produced, increasing the composition of oxygen
  • As plants evolved, more carbon dioxide taken in, decreasing the composition of carbon dioxide
• Describe some of the health issues caused by the products of combustion of a fuel, such as wood.

  [4 marks]

  Allow any four from:

  • Carbon monoxide produced
  • Carbon monoxide is a toxic gas – can kill
  • Particulates / carbon / soot produced
  • Particulates / carbon / soot can worsen asthma symptoms / irritate lung linings / may cause cancer
  • Sulfur dioxide / oxides of nitrogen produced
  • Sulfur dioxide / oxides of nitrogen causes respiratory problems in humans
• Some people in favour of wood burners say:“Wood burners provide a sustainable way to provide heat compared to other methods such as gas central heating.”

  Explain how.

  [2 marks]

  Any two from:

  • Wood can be regrown quicker than it is used up
  • However, natural gas is a finite resource
  • Gas takes millions of years to form
  • Natural gas will run out in the foreseeable future
• Wood burners are an example of a use for Earth’s natural resources. They burn wood to provide warmth.Give two other uses of Earth’s natural resources.

  [2 marks]

  – Any two from:

  1. Food from farming
  2. Fuels for transport
  3. Building materials to provide shelter
  4. Materials for clothing
• Two common alternative methods to measure the rate of reaction are:

  1. Measure the volume of gas produced over time – using a gas syringe or an inverted measuring cylinder in water.
  2. Observe the change in mass – place the reaction on a balance and measure the decrease in mass as gas escapes.
• Discuss the supply and demand of crude oil fractions.Include in your answer an explanation of how any problems arising from this are overcome.

  [6 marks]

  Relevant content:

  • Shorter chain hydrocarbons make up gases, petrol, kerosene and diesel.
  • The demand for these fractions is higher than the supply.
  • Longer chain hydrocarbons make up fuel oil and bitumen.
  • The demand for these fractions is lower than the supply.
  • Cracking converts longer chain hydrocarbons into shorter chain hydrocarbons.
  • Long-chain alkanes/hydrocarbons are broken down into alkanes and alkenes of shorter length.
  • The shorter chain alkanes produced by cracking can be used to make the more in demand fractions e.g. petrol.
  • The alkenes produced can be used in making polymers and ethanol.
• Evaluate the use of aluminium cans and plastic bottles for drink containers.Use the life cycle assessment (LCA) above and your own knowledge.

  [5 marks]

  Any five from:

  • Both aluminium and plastic (crude oil) are non-renewable resources.
  • Aluminium is a finite resource / will run out.
  • Crude oil is a finite resource / will run out.
  • Aluminium cans require more than double the energy of plastic bottles per unit.
  • Aluminium cans consume about 18 times more / more water than plastic bottles per unit.
  • Aluminium cans emit more / about twice as much CO₂ as plastic bottles per unit.
  • Plastic bottles produce more waste if not recycled due to lower recycling rates and higher volumes ending up in landfills or oceans.
• Compare the ease of obtaining potable water from wastewater, groundwater, and saltwater based on the data in the table.Consider treatment required, energy use, cost, and time to purify.

  [4 marks]

  Any four from:

  • Saltwater requires the most energy, time, and money to purify.
  • Groundwater requires the least energy, time, and money to purify.
  • Saltwater requires a lot of energy because distillation/reverse osmosis is required to remove salt.
  • Groundwater only requires filters and sterilisation, which requires low energy/is a simple process.
  • Wastewater contains organic matter/harmful microbes/harmful chemicals which must be removed.
  • Wastewater requires sedimentation and treatment with aerobic bacteria to remove harmful microorganisms.
• Wastewater is considered the most complex to treat, yet it can provide a large volume of water, and it produces a by-product called sludge which can be processed to produce a fuel.

  Describe how fuel is formed from wastewater.

  [4 marks]

  Indicative content – Any four from:

  • Wastewater undergoes screening and grit removal
  • Sewage is left so the solid sediment sinks to the bottom and the liquid sits on top
  • The solid sediment is called sludge
  • Anaerobic bacteria are added
  • Absence of oxygen
  • Bacteria break down the organic matter
  • The anaerobic digestion of sludge produces biogas – a fuel
  • Remaining sludge can be dried out and burnt as a fuel