C11: Air and Water

Water
  • The presence of water can be tested through using copper(II) sulfate and cobalt(II) chloride
  • When white copper(II) sulfate is added to water, it turns blue
  • When cobalt (II) chloride
  • Water has to be treated to be usable
  • Filtration is used to separate larger impure particles from water. This is done by using a filter and pouring water through it
  • Chlorination separates water from smaller organisms that cannot be separated with filtration. It is done by adding chlorine to water to kill the smaller organisms (eg. bacteria)
  • Drinking unclean water may causes diseases such as chloera and typhoid


Air
  • Clean, unpolluted air is a mixture of 78% nitrogen, 21% oxygen, and around 1% of noble gases, water vapour, and carbon dioxide
  • Air (with the presence of oxygen and water) causes iron to rust
  • Rust is prevented through coating iron with layers such as paint or other coatings like zinc
  • Galvanising is coating iron with zinc, which prevents rust by stopping oxygen and water from reaching the iron. It reacts with the oxygen as well, due to its reactivity (which is higher than iron), making it a sacrificial metal that reacts with oxygen in place of iron
  • Air is polluted by...
    • Carbon monoxide
      • Released by incomplete combustion of fossil fuels (when carbon is released from burning fuels in a poor supply of oxygen)
      • Carbon monoside is poisonous and causes hemoglobin in the blood to not carry oxygen as well
    • Sulfur dioxide
      • Released after combusting fuels, natural gases, and sulfide ores
      • The presence of sulfur dioxide in the air causes acid rain, corroding metal. It also pollutes crops and water, and causes discomfort in the lungs, throats, and eyes
      • It's emissions can be reduced by using low sulfur petrol, and using spraying sulfur dioxide emissions with calcium oxide to neutralise the acid and reduce pollution
    • Nitrogen oxides
      • Released from reaction of car engines and furnances with nitrogen. Also released from reactions in the soil with bacteria
      • It is dangerous as it causes acid rain and a smog, which may cause difficulty breathing, especially for asthma


Catalytic converters

  • Catalytic converters in car exhaust pipes remove nitrogen monoxide and carbon dioxide through reactions with a heated catalyst
  • A transition metal acts as a catalyst on the converter
  • A series of reactions take place, which are...
    • 2CO + O2 → 2CO2
    • 2NO + 2CO → N2 + 2CO2
    • 2NO → N2 + O2
  • Therefore, carbon monoxide is removed as it forms carbon dioxide and nitrogen monoxide is removed as it forms nitrogen gas and another product


Carbon dioxide and methane

Carbon Dioxide is formed in many ways. It is formed as a product of...

  • Complete combustion of carbon-containing substances
  • Respiration
  • A reaction between an acid and carbonate
  • Thermal decomposition of calcium carbonate


Carbon dioxide and methane are greenhoiuse gases, which cause an enhanced greenhouse effect, contributing towards climate change through the absorption of heat in the atmosphere



Nitrogen and fertilisers
  • Fertilisers containing nitrogen, phosphorus, and potassium
  • Nitrogen fertilisers are used for more healthy leaves as it is a big component of chlorophyll, which confucts photosynthesis
  • Potassium fertilisers are used for the plants to grow and develop healthy fruit and flowers
  • Phosphorus fertilises are used for the plants to develop healthy roots


Displacement of ammonia

  • Ammonia can be separated from a salt through reactions with an alkali
  • Basic substances are often added to soil to make it less acidic
  • When basic substances have been added in soil in excessive amounts or right after fertiliser has been added, ammonia might be displaced from the soil, causing a loss of nitrogen
  • When there is less nitrogen in the soil, it does not fertilise plants as well (meaning that they grow less healthy leaves)


Manufacturing ammonia

  • Ammonia is manufactured by the Haber process, which has 5 main steps
    1. Air and natural gas contain H2 and N2, which is drawn out to be pumped through a pipe into a compressor
    2. The H2 and N2 are compressed in the compressor
    3. The compressed gases travel into a tank of high temperature where some of the H2 and N2 react to form ammonia (NH3)
    4. The H2 and N2 that had not reacted go into a cooling tank, while the ammonia in step 3 are made into a liquid and moved to pressured storage vessels
    5. The remaining gases that did not react are taken from the cooling tank to be used again to react


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