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Karteikarten

Water

Adrianna Bialecka Chemistry Leaving Certificate Englisch 40 Karten

Karten in diesem Stapel (40)

  1. 1What is Hard Water?it is water that will not easily form a lather with soap. It is caused by Ca+2/Mg+2 ions in the water
  2. 2What is temporary Hardness?It is hardness that can be removed by boiling
  3. 3What causes temporary hardness?Calcium/Magnesium hydrogen carbonates
  4. 4How does Calcium hydrogen carbonate form?H2O + CO2 -> H2CO3
    H2CO3 + CaCO3 -> Ca(HCO3)2
  5. 5What test can be used to test for the presence of limescale deposits on kettle?CaCO3 + 2HCL -> CaCl2 + H2O + CO2
    we use limewater to test if CO2 formed when HCl added. If limewater turns milky it means carbon dioxide is present
  6. 6How do we remove temporary hardness?BOILING
    Ca(HCO3)2 -> CaCO3 + H2O + CO2
  7. 7What is permanent hardness?It is hardness that cannot be removed by boiling
  8. 8What causes permanent hardness?Calcium/Magnesium Sulfates/Chlorides
  9. 9How do you remove permanent hardness?Water is passed through ion-exchange resin
    Ca+2 + 2RNa -> R2Ca + 2Na+
  10. 10How is deionised water made?1. -> RH + Na+ -> RNa + H+
    -> ROH + Cl- -> RCl + OH-
    2. H+ + OH- -> H2O
  11. 11What's the difference between deionised and distilled water?Both have no ions but deionised water has dissolved gases while distilled water has no dissolved gases
  12. 12What are the seven stages in water treatments?SFSFCFpH
    1. Screening
    2. Flocculation
    3. Sedimentation
    4. Filtration
    5. Chlorination
    6. Fluoridation
    7. pH adjustment
  13. 13Describe screening in water treatmentWater is passed through a wire mesh to remove any floating debris
  14. 14Describe Flocculation in water treatmentIt is the coagulation of small suspended particles in water into flocs
  15. 15What is a flocculating agent?Aluminium sulfate (Al2(SO4)3)
    However in excess affects taste and causes corrosion of pipes
  16. 16Describe sedimentation in water treatmentFlocs settle to bottom of settlement tank
  17. 17Describe Filtration in water treatmentWater is passed through large beds of sand and gravel which remove suspended solids
  18. 18Describe Chlorination in water treatmentChlorine sterilises water and kills any harmful microbes. 0.5 ppm is the ideal amount.
    Excess can affect the smell and taste and can also be toxic
  19. 19Describe Fluoridation in water treatment1 p.p.m of NaF is added to reduce tooth decay and strengthen teeth enamel.
    Excess can be toxic and stains teeth
  20. 20Describe pH adjustment in water treatmentOptimum pH for water is 7.2
    If water supply too acidic is can corrode pipes and be bad for teeth
    We add Calcium hydroxide to raise pH above 7
    If pH is too high, dilute sulfuric acid can be added
  21. 21What is Eutrophication?It is the over enrichment of water with nutrients such as nitrates and phosphates
  22. 22What are the causes of Eutrophication?Addition of sewage, animal slurry etc. Artificial fertilisers especially add a lot of NO3- and PO4-3
  23. 23What is the effect of Eutrophication?Excessive growth of algae and other plants. The algae decays and bacteria feed on this. As bacteria break down the algae they use up the oxygen dissolved in the water. This causes levels of oxygen to fall too low and fish die
  24. 24What is BOD?it is the quantity of dissolved oxygen consumed by biochemical action in a water supply over 5 days in the dark at 20 degrees celsius
  25. 25What are examples of heavy metal ions?Lead ions (Pb+2), mercury ions (Hg+2) and cadmium ions (Cd+2)
  26. 26How do heavy metal ions get into water?People dumping batteries
  27. 27Why are heavy metal ions bad?They are cumulative poisons
  28. 28How are heavy metal ions removed from water?Precipitation and filtration. e.g. lead ions react wit dilute HCl and the lead is precipitated as lead chloride
    Pb+2 + 2HCl -> PbCl2 + 2H+
  29. 29What are the EU limits for nitrates in water?50 mg/L
  30. 30What are the EU limits for phosphates in water?0.5-0.7 mg/L
  31. 31What do we use the AAS for?Measuring the concentration of heavy metal in water
  32. 32What does AAS stand for?Atomic Absorption Spectrometry
  33. 33What are the 3 stages of Sewage Treatment?1. Primary treatment
    2. Secondary treatment
    3. Tertiary treatment
  34. 34What is primary treatment?It is a physical process in which solids are removed by screening and some suspended solids are removed by settling
  35. 35What is secondary treatment?It is the breakdown of sewage by biological actions by pumping the sewage into an aeration tank full of bacteria
  36. 36What is Tertiary Treatment?Is is a process to reduce/remove nitrates and phosphates in order to prevent eutrophication
  37. 37How are nitrates broken down?Biologically by denitrifying bacteria
  38. 38How are phosphates broken down?Chemically by precipitation. This occurs by adding Al2(SO4)3
    Al+3 + PO4+3 -> AlPO4
  39. 39How is pH measured?Using pH paper
  40. 40What is the principle of colorimetry?It is that the intensity of the colour of a solution is proportional to its concentration

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Leaving Certificate Chemistry (Water) Karteikarten am Water, erstellt von Adrianna Bialecka am 08/12/2022.
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Adrianna Bialecka
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