CWEA LABORATORY ANALYST EXAM
Terms in this set (169)
Chloride - Major anion found in many natural waters
- Can impart salty taste in H2O
What increases concentration of chloride in wastewater Chloride in human diet and softeners flushed into sanitary sewer system
2 most prevalent methods of measuring chloride argentometric and mercuric nitrate
Argentometric Titration of sample with standard solution of silver nitrate (AgNO3)
- Indicator: Chromate ions (CrO4)
- End point: reddish silver chromate
Mercuric Nitrate Titration with standard mercuric nitrate solution
-pH must be adjusted between 2.3 and 2.8
- Indicator: Diphenyl carbazone
- End point: Change from blue to purple in presence of mercury
Interference of Mercuric Nitrate Method Sulfide, bromide, orthophosphate (over 30 ppm), and iodide
Why does color change in water Presence of decaying vegetable matter, metal ions (ie. iron) or industrial and
domestic pollution
How is color measured Measured using visual comparison method
Visual comparison method Sample compared to standards using matched nessler tubes
- Standards prepared with solution containing cholorplatinate and cobaltous
chloride
Standard units for color One unit= color resulting from 1 mg of platinum/L
2 color reporting True and Apparent
True color Color from dissolved substances, determine using sample treated to remove
turbidity
, CWEA LABORATORY ANALYST EXAM
Apparent Color Includes dissolved and suspended solids
Conductivity H2Os capability to pass electrical flow
Conductivity of pure water 0
Units of conductivity micromhos/cm
Temperature conductivity should be read at 25 degrees Celcius
How is conductivity affected Mobility of ions, conductivity is dependent on viscosity
Viscosity A liquids ability to resist flow, higher the viscosity the lower the flow
Relationship of temperature and viscosity Inverse
Acid A compound which liberates hydrogen ions and has a pH below 7.
Alkalinity: The measurement of a sample's capacity to neutralize acid.
Alkalinity measures The carbonate, bicarbonate, and hydroxide ion concentration found in water
Primary reason for measuring alkalinity Used in control of many water and wastewater unit processes
How is alkalinity measured Titration of a sample with a standard solution of either sulfuric acid or
hydrochloric acid to predetermined pH endpoint
The phenolphthalein alkalinity of a water sample is zero The pH is greater than 8.3
if:
Atomic Weight: The sum of the number of protons and the number of neutrons in the nucleus
of an atom.
Atomic weights of elements are found on periodic tables.
Base: A compound which liberates hydroxide ions and has a pH above 7.
Biochemical Oxygen Demand (BOD): The quantity of oxygen utilized in the biochemical oxidation of organic
matter under standard laboratory procedures for five days at 20° Centigrade,
usually expressed as a
concentration (e.g., mg/L). BOD measurements are used to indicate the organic
"strength" of wastewater.
Terms in this set (169)
Chloride - Major anion found in many natural waters
- Can impart salty taste in H2O
What increases concentration of chloride in wastewater Chloride in human diet and softeners flushed into sanitary sewer system
2 most prevalent methods of measuring chloride argentometric and mercuric nitrate
Argentometric Titration of sample with standard solution of silver nitrate (AgNO3)
- Indicator: Chromate ions (CrO4)
- End point: reddish silver chromate
Mercuric Nitrate Titration with standard mercuric nitrate solution
-pH must be adjusted between 2.3 and 2.8
- Indicator: Diphenyl carbazone
- End point: Change from blue to purple in presence of mercury
Interference of Mercuric Nitrate Method Sulfide, bromide, orthophosphate (over 30 ppm), and iodide
Why does color change in water Presence of decaying vegetable matter, metal ions (ie. iron) or industrial and
domestic pollution
How is color measured Measured using visual comparison method
Visual comparison method Sample compared to standards using matched nessler tubes
- Standards prepared with solution containing cholorplatinate and cobaltous
chloride
Standard units for color One unit= color resulting from 1 mg of platinum/L
2 color reporting True and Apparent
True color Color from dissolved substances, determine using sample treated to remove
turbidity
, CWEA LABORATORY ANALYST EXAM
Apparent Color Includes dissolved and suspended solids
Conductivity H2Os capability to pass electrical flow
Conductivity of pure water 0
Units of conductivity micromhos/cm
Temperature conductivity should be read at 25 degrees Celcius
How is conductivity affected Mobility of ions, conductivity is dependent on viscosity
Viscosity A liquids ability to resist flow, higher the viscosity the lower the flow
Relationship of temperature and viscosity Inverse
Acid A compound which liberates hydrogen ions and has a pH below 7.
Alkalinity: The measurement of a sample's capacity to neutralize acid.
Alkalinity measures The carbonate, bicarbonate, and hydroxide ion concentration found in water
Primary reason for measuring alkalinity Used in control of many water and wastewater unit processes
How is alkalinity measured Titration of a sample with a standard solution of either sulfuric acid or
hydrochloric acid to predetermined pH endpoint
The phenolphthalein alkalinity of a water sample is zero The pH is greater than 8.3
if:
Atomic Weight: The sum of the number of protons and the number of neutrons in the nucleus
of an atom.
Atomic weights of elements are found on periodic tables.
Base: A compound which liberates hydroxide ions and has a pH above 7.
Biochemical Oxygen Demand (BOD): The quantity of oxygen utilized in the biochemical oxidation of organic
matter under standard laboratory procedures for five days at 20° Centigrade,
usually expressed as a
concentration (e.g., mg/L). BOD measurements are used to indicate the organic
"strength" of wastewater.
