chemistry mistakes and should be memorized

• what are the steps of purification of water

  screening

  sedimentation

  filtration

  carbon filter

  chlorination
• explain how sand filters work

  remove insoluble impurities

  sand has small pores which only pass water molecules
• other ways of obtaining pure water?

  fractional distillation

  of sea water
• test of presence of water?

  anhydrous copper 2 sulfate turns white to blue

  anhydrous cobalt 2 chloride turns blue to pink
• test for purity of water?

  heat sample

  pure water has sharp and fixed boiling point

  at 100 degrees
• uses of water in industry?

  coolant

  solvent

  agriculture irrigation
• why is tap water considered polluted

  contains dissolved impurities

  due to human activities
• what are the beneficial substances found in water

  dissolved oxygen > supports marine life > comes from photosynthesis

  metallic elements > minerals good for body > like calcium and iron
• what are the harmful substances found in water

  metallic compounds > like lead > comes from mining and waste disposal

  
  

  sewage > causes diarhea and polio > comes from human wastes > released into water due to leaks of sewage > due to natural disasters

  
  

  phosphates and nitrates > comes from NPK fertiliser runoff > causes growth of algal bloom > blocks light and no photosynthesis occurs > causes death of aquatic plants

  
  

  plastics > comes from insoluble polymers > because they are non biodegradable
• uses of oxygen

  production of steel

  breathing for sick people

  oxyacetylene flame in cutting and welding
• uses of carbon dioxide

  fizzy drinks

  fire extinguisher
• what are the common pollutants found in air

  unburnt hydrocarbons

  carbon monoxide

  carbon dioxide

  methane

  sulfur dioxide

  oxides of nitrogen

  lead compounds

  carbon particulates
• source of carbon monoxide?

  incomplete combustion of fossil fuels
• source of carbon dioxide?

  complete combustion of fossil fuels

  respiration
• source of methane gas?

  vegetation decomposition

  cattle farming
• source of sulfur dioxide?

  combustion of fossil fuels containing sulfur
• source of nitrogen oxides?

  lightening

  car engines
• source of carbon particulates?

  incomplete combustion in diesel cars
• removal of carbon monoxide and unburnt hydrocarbons

  catalytic convertor
• adverse effects of oxides of nitrogen and sulfur dioxide

  acid rain
• another adverse effect of oxides of nitrogen

  photochemical smog
• equations of catalytic convertor

  2CO + 2NO > 2CO2 + N2

  2NO > N2 + O2

  2CO + O2 > 2CO2
• removal process of sulfur dioxide

  flue gas desulphurization by adding CaO
• name a compound which will displace ammonia from ammonium nitrate

  calcium hydroxide
• whats a strong base

  proton acceptor

  accepts protons more readily
• what is a proton

  Hydrogen ion
• another way to describe displacement reactions

  redox reactions
• observations of displacement of non metals

  colorless to reddish brown
• common reducing agent? {6}

  carbon

  carbon monoxide

  hydrogen

  potassium iodide

  sulphur dioxide

  Fe+2 coumpounds
• amphoteric oxides?

  Al2O3
• common oxidizing agent

  halogens

  pottasium manganate

  hydrogen peroxide

  Fe+3
• hydrogen peroxide equation?

  H2O2 > 2H2O +O2

  MnO2 catalyst
• Lithium Nitrate has a formula of Li3N. Why?

  different valencies

  charges cancel each other out