using resources

• How do you make potable water.


  Water from a reservoir is treated by firstly filtering lake water to remove solids like leaves. then it is treated using either uv light, ozone, or chlorine which kill microbes in the water and make it safe to drink
• in country’s with less water you make drinking water and you use sea water so you must remove salt in a process called desalination where salt is removed by evaporation water to get it 100% pure
• Explain why you galvanizing iron with zinc would protect it 


  Zinc is more reactive than iron on the reactivity series. The more reactive metal(zinc) is used to coat iron so it rusts the zinc but keeps the iron in tact

  tus is known as sacrificial protection.
• rust equation given that rust is hydrated iron (|||) oxide.

  Iron+oxygen+water->hydrated iron(|||) oxide
• Name the 3 useful alloys 


  Brass=an alloy of copper and zinc

  bronze=an alloy of copper and tin

  steel=an alloy of iron and carbon
• Why are alloys stronger their pure form.

  In an alloy different metal ions distort the layer. this makes it more difficult for layers to slide over each other when a force is applied. This makes alloys harder than the pure metals
• Given that a composite is a metal made up of a matrix and reinforcement material. what is a matrix and a reinforcement


  A matrix is a binder that distributes the force. it also binds the reinforcement material together.

  the reinforcement material is the thing that gives the composite strength
• What is a composite example 


  Stainless steel
• What are uses of borosilicate glass in everyday life given that it can handle really high Pressures and doesn’t shatter 


  Oven door windows, science equipment, glasses, glass cooking ware.
• Metal is used for wires as…

  its a good conductor of electricity
• what is potable water?


  water that is suitable for human consumption (i.e., water that can be used for drinking or cooking). 
• what is pure water in chemistry?

  pure water literally only contains H2O.
• what is desaltinisation?

  Potable water can be made from sea water, through a process known as desalination. It is preferable to make potable water from fresh water reserves rather than from sea water. This is because removing the large amount of sodium chloride (35 grams in every kilogram of sea water) requires a lot of energy.
• how can desalination be done?

  Desalination can be done by distillation and by reverse osmosis.
• Reverse osmosis

  Water is put under high pressure and passed through a membrane which has tiny pores (holes) in it. The pores allow water molecules through, but prevent most ions and molecules from passing through. Reverse osmosis requires expensive membranes and also produces a large volume of waste water, so its efficiency is often quite low.
• Distillation

  Sea water is heated until it boils. The salt remains in the liquid, and the steam is pure water. The steam is cooled and condensed to make potable water.

  Distillation requires a lot of energy to boil the water, and also to cool the steam down to condense it. The waste water is very salty and can be difficult to dispose of in a sustainable way which does not harm marine ecosystems.
• Which method of water purification would be best suited to a country in the Middle East which has a large amount of fossil fuel reserves?

  Distillation would be the most appropriate method of desalination because the country would be able to use fossil fuels to provide the energy needed at a relatively low cost.
• how to treat sewage...

  1. screening and grit removal to remove large particles
  2. sedimentation allows tiny particles to settle out from still water, which produces sewage sludge and effluent (the liquid which remains on top)
  3. the sewage sludge is digested anaerobically by specific bacteria
  4. the effluent is treated with aerobic bacteria to reduce the volume of solid waste
• how hard is an alloy...?


  In the solid state, a pure metal has a giant metallic structure. The atoms are arranged in layers. When a force is applied, the layers may slide over each other. The greater the force needed, the harder and stronger the metal.

  
• Explain why steel, which is an alloy of iron, is harder than pure iron.


  Steel contains atoms of other elements as well as iron. These atoms have different sizes to iron atoms, so they distort the layers of atoms in the pure iron. This means that a greater force is required for the layers to slide over each other in steel, so steel is harder than pure iron.
• The ground water is not chemically pure because the water contains sodium ions and chloride ions.

  Suggest what the company means by ‘pure’.


  has all the mineral and particle pollutants removed from it.
• Suggest why alloys do not conduct electricity as well as pure metals.


  in alloys different sized atoms distort the layers / structure (so) the movement of (delocalised) electrons is restricted
• Give the best method for obtaining pure water from seawater.

  reverse osmosis, distillation
• Explain how distillation can be used to make potable water from salty water 


  Heat/boil salty water-Water evaporates/water vapor formed— water vapour then cooled- then condenses to form liquid water/potable water
• Distillation is expensive because….


  it requires a lot of energy.
• explain why graphite is a good conductor of electricity.

  Graphite is a good conductor of electricity because it has delocalized electrons. In graphite, each carbon atom forms three covalent bonds, leaving one electron free. These free electrons can move through the layers of carbon atoms, allowing electricity to flow. This makes graphite a good conductor, even though it is a non-metal.
• explain why graphite is soft and slippery.

  no covenant bonds between layers, so layers can slide over each other, so graphite is soft and slippy.
• why is copper suitable for wires?

  • It has high electrical conductivity (due to free delocalised electrons).

  • It is ductile, meaning it can be stretched into thin wires.

  • It is resistant to corrosion.
• why is copper resistant to corrosion?

  Formation of a protective layer:

  • Copper reacts with oxygen in the air to form a thin layer of copper oxide (Cu₂O).

  • Over time, this layer can develop into a green coating called patina (copper carbonate), which protects the underlying metal from further corrosion.

  
  

   Low reactivity:

  • Copper is a relatively unreactive metal, meaning it does not easily react with water or acids under normal conditions.

  • It is lower in the reactivity series, so it does not corrode as quickly as metals like iron.
• Suggest why alloys do not conduct electricity as well as pure metals.

  in alloys different sized atoms distort the layers / structure (so) the movement of (delocalised) electrons is restricted
• what is the alloy bronze made from?

  Copper and tin
• Suggest an explanation for why magnalium is used to make aircraft parts.

  Magnalium alloy is stronger than aluminium but still has a low density. This makes it suitable for aircraft parts, which must be light and also strong.
• describe how iron conducts thermal energy

  iron is a transition metals which means its delocalized electrons are able to carry thermal energy through the metal.
• what is a transition metal?


  a group of elements in the periodic table that have unique properties and are found in the middle of the table

  
• Describe how sewage is treated to remove organic matter.


  screening, filtering to remove (large) solids, sedimentation (to produce sewage sludge and effluent) , anaerobic digestion of (solid sewage) sludge , aerobic biological treatment of (liquid) effluent
• explain why Exposing water to ultraviolet light makes it safe to drink?

  (the ground water) contains microbes which are harmful (to health) (so) the water is sterilised or (so) the microbes are destroyed.
• Ground water is not chemically pure because the water contains sodium ions and chloride ions. Suggest what the company means by ‘pure’.


  (the water is) unadulterated or (the water) contains no microbes
• The building material consists of a wood particle reinforcement embedded in a poly(ethene) matrix. What general name is given to materials like this?

  composites
• what is the Haber process?

  he industrial method for making ammonia (NH₃) from nitrogen (N₂) and hydrogen (H₂).

  
• what conditions are needed for the Haber process

  • Iron catalyst

  • 450°C temperature

  • 200 atm pressure