Chapter 19: Water Flashcards
Hard water
Water that does not easily form a lather in soap
Causes by Ca2+ or Mg2+ ions I’m water
How is Scum formed
Calcium or magnesium ions react with stearate ions to form calcium stearate (scum)
Temporary Hardness
One that can be removed by boiling water
• Caused by calcium hydrogen carbonate
Permanent Hardness
Hardness that cannot be removed by boiling
Magnesium sulfate, calcium sulfate
Methods of Removing Hardness
Distillation
Zeolites
Washing soda
Ion-exchange resin
Distilled water
Purest form
All dissolved and suspended solids and all dissolved gases removed
Buffer Solution
A solution that resists changes in pH
Water Treatments Stages
Screening Flocculation Sedimentation Filtration Chlorination Fluoridation pH adjustment
Flocculation
The coagulating of small suspended particles in water
Aluminium sulfate
Primary Treatment
Screening
Channels Settlement
Secondary Treatment
Oxidation and aeration of sewage
Micro-organisms decompose sewage
Tertiary Treatment
Prevention of eutrophication by removing nitrates and phosphates
Instruments to Analyse Water
pH measurement
AAS - Atomic Absorption Spectrometry
Colorimetry
Colorimetry
Amount of absorbance of light is proportional to the concentration of the solution
Free Chlorine
Chlorine that exists in the water as hypochlorous acid and hypochlorite ion