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CWEA Grade I Laboratory Analyst Exam 2025
Chloride - .....ANSWER ...✔✔ - Major anion found in
many natural waters
- Can impart salty taste in H2O
What increases concentration of chloride in wastewater
- .....ANSWER ...✔✔ Chloride in human diet and
softeners flushed into sanitary sewer system
2 most prevalent methods of measuring chloride -
.....ANSWER ...✔✔ argentometric and mercuric nitrate
Argentometric - .....ANSWER ...✔✔ Titration of
sample with standard solution of silver nitrate (AgNO3)
- Indicator: Chromate ions (CrO4)
- End point: reddish silver chromate
Mercuric Nitrate - .....ANSWER ...✔✔ Titration with
standard mercuric nitrate solution
-pH must be adjusted between 2.3 and 2.8
- Indicator: Diphenyl carbazone
,2|Page
- End point: Change from blue to purple in presence of
mercury
Interference of Mercuric Nitrate Method - .....ANSWER
...✔✔ Sulfide, bromide, orthophosphate (over 30
ppm), and iodide
Why does color change in water - .....ANSWER ...✔✔
Presence of decaying vegetable matter, metal ions (ie.
iron) or industrial and domestic pollution
How is color measured - .....ANSWER ...✔✔
Measured using visual comparison method
Visual comparison method - .....ANSWER ...✔✔
Sample compared to standards using matched nessler
tubes
- Standards prepared with solution containing
cholorplatinate and cobaltous chloride
Standard units for color - .....ANSWER ...✔✔ One
unit= color resulting from 1 mg of platinum/L
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2 color reporting - .....ANSWER ...✔✔ True and
Apparent
True color - .....ANSWER ...✔✔ Color from dissolved
substances, determine using sample treated to remove
turbidity
Apparent Color - .....ANSWER ...✔✔ Includes
dissolved and suspended solids
Conductivity - .....ANSWER ...✔✔ H2Os capability to
pass electrical flow
Conductivity of pure water - .....ANSWER ...✔✔ 0
Units of conductivity - .....ANSWER ...✔✔
micromhos/cm
Temperature conductivity should be read at -
.....ANSWER ...✔✔ 25 degrees Celcius
How is conductivity affected - .....ANSWER ...✔✔
Mobility of ions, conductivity is dependent on viscosity
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Viscosity - .....ANSWER ...✔✔ A liquids ability to resist
flow, higher the viscosity the lower the flow
Relationship of temperature and viscosity - .....ANSWER
...✔✔ Inverse
Acid - .....ANSWER ...✔✔ A compound which liberates
hydrogen ions and has a pH below 7.
Alkalinity: - .....ANSWER ...✔✔ The measurement of a
sample's capacity to neutralize acid.
Alkalinity measures - .....ANSWER ...✔✔ The
carbonate, bicarbonate, and hydroxide ion
concentration found in water
Primary reason for measuring alkalinity - .....ANSWER
...✔✔ Used in control of many water and wastewater
unit processes
How is alkalinity measured - .....ANSWER ...✔✔
Titration of a sample with a standard solution of either
CWEA Grade I Laboratory Analyst Exam 2025
Chloride - .....ANSWER ...✔✔ - Major anion found in
many natural waters
- Can impart salty taste in H2O
What increases concentration of chloride in wastewater
- .....ANSWER ...✔✔ Chloride in human diet and
softeners flushed into sanitary sewer system
2 most prevalent methods of measuring chloride -
.....ANSWER ...✔✔ argentometric and mercuric nitrate
Argentometric - .....ANSWER ...✔✔ Titration of
sample with standard solution of silver nitrate (AgNO3)
- Indicator: Chromate ions (CrO4)
- End point: reddish silver chromate
Mercuric Nitrate - .....ANSWER ...✔✔ Titration with
standard mercuric nitrate solution
-pH must be adjusted between 2.3 and 2.8
- Indicator: Diphenyl carbazone
,2|Page
- End point: Change from blue to purple in presence of
mercury
Interference of Mercuric Nitrate Method - .....ANSWER
...✔✔ Sulfide, bromide, orthophosphate (over 30
ppm), and iodide
Why does color change in water - .....ANSWER ...✔✔
Presence of decaying vegetable matter, metal ions (ie.
iron) or industrial and domestic pollution
How is color measured - .....ANSWER ...✔✔
Measured using visual comparison method
Visual comparison method - .....ANSWER ...✔✔
Sample compared to standards using matched nessler
tubes
- Standards prepared with solution containing
cholorplatinate and cobaltous chloride
Standard units for color - .....ANSWER ...✔✔ One
unit= color resulting from 1 mg of platinum/L
,3|Page
2 color reporting - .....ANSWER ...✔✔ True and
Apparent
True color - .....ANSWER ...✔✔ Color from dissolved
substances, determine using sample treated to remove
turbidity
Apparent Color - .....ANSWER ...✔✔ Includes
dissolved and suspended solids
Conductivity - .....ANSWER ...✔✔ H2Os capability to
pass electrical flow
Conductivity of pure water - .....ANSWER ...✔✔ 0
Units of conductivity - .....ANSWER ...✔✔
micromhos/cm
Temperature conductivity should be read at -
.....ANSWER ...✔✔ 25 degrees Celcius
How is conductivity affected - .....ANSWER ...✔✔
Mobility of ions, conductivity is dependent on viscosity
, 4|Page
Viscosity - .....ANSWER ...✔✔ A liquids ability to resist
flow, higher the viscosity the lower the flow
Relationship of temperature and viscosity - .....ANSWER
...✔✔ Inverse
Acid - .....ANSWER ...✔✔ A compound which liberates
hydrogen ions and has a pH below 7.
Alkalinity: - .....ANSWER ...✔✔ The measurement of a
sample's capacity to neutralize acid.
Alkalinity measures - .....ANSWER ...✔✔ The
carbonate, bicarbonate, and hydroxide ion
concentration found in water
Primary reason for measuring alkalinity - .....ANSWER
...✔✔ Used in control of many water and wastewater
unit processes
How is alkalinity measured - .....ANSWER ...✔✔
Titration of a sample with a standard solution of either
