Earth and Air

• What are the three main greenhouse gases?

  1. Water vapour
  2. Carbon dioxide
  3. Methane
• What is the process for obtaining potable water from groundwater?

  First, the water is filtered to remove any insoluble solids.

  Then, a flocculating agent is added to remove any other molecules.

  Finally the water is cleaned and purified using ozone, chlorine, or UV light to kill any microbes.
• How is potable water obtained from sewage?

  First, the sewage is screened using a metal grid to remove large objects or sediment.

  Then, the solid waste and liquid waste are separated.

  The liquid waste known as effluent is aerobically digested before being treated and discharged.

  Meanwhile, the solid waste or sludge is anaerobically digested and used as fertiliser or fuel.
• What is a carbon footprint?

  How much carbon and other greenhouse gases a person, process, or product uses.
• What is the difference between LDPE and HDPE?

  LDPE has side branches which weaken the forces of attraction and means that it has a lower density, strength, and boiling point than HDPE.
• What is the difference between thermoforming and thermosetting polymers?

  Thermoforming: Can be reshaped when heated. Thermosetting: Cannot be reshaped once set.
• What are the properties of clay ceramics?

  Hard, brittle, electrically insulative, and unreactive.
• What is a composite?

  A material made from 2 materials: one acting as a binder for the other.
• What is the most common type of glass and what is it made of?

  Soda-lime glass

  made from: sand, limestone, and sodium carbonate
• What does an LCA look at?

  • Raw materials
  • Manufacture
  • Usage
  • Disposal
• What are the proportion of gases in the atmosphere?

  Nitrogen (78%)

  Oxygen (21%)

  Other gases e.g Carbon Dioxide (1%)
• How has the atmosphere evolved?

  Volcanic activity released water vapour and nitrous oxides. The water vapour condensed to form oceans which carbon dioxide dissolved into.

  Algae and plants evolved and absorbed carbon dioxide for photosynthesis which also released oxygen.
• How do greenhouse gases cause global warming?

  .Heat from the Sun as short-wave radiation passes through to heat the Earth's surface. The Earth's surface then reflects some of this heat as long-wave radiation. Some of this heat is then trapped by greenhouse gases, which radiate the heat back towards Earth causing global warming.
• Incomplete combustion leads to the production of particulates or soot. What are the effects of this?

  Forms clouds of smog which reflect light back to space and cause respiratory problems as the particles damage our lungs.
• Why is carbon monoxide harmful to humans?

  When we breathe in carbon monoxide it diffuses into our bloodstream and binds to our haemoglobin reducing the amount of oxygen that can be carried so less oxygen is transported to the tissues, which can cause symptoms such as fainting, comas and death.
• When burning fossil fuels, how is sulphur dioxide formed?

  Sulphur is an impurity in some fossil fuels and is oxidised when they're combusted.
• When burning fossil fuels in an engine, how are nitrogen oxides formed?

  Nitrogen from the air is oxidised at the high temperature inside the engine.
• What causes acid rain?

  Sulphur dioxide or nitrogen oxides