Page | 1
CWEA LABORATORY ANALYST EXAM
ALL GRADES 2026 QUESTIONS AND
ANSWERS | A+ GRADED | WITH
EXPERT SOLUTIONS
Chloride - correct answer-- Major anion found in many natural
waters
- Can impart salty taste in H2O
What increases concentration of chloride in wastewater - correct
answer-Chloride in human diet and softeners flushed into sanitary
sewer system
2 most prevalent methods of measuring chloride - correct answer-
argentometric and mercuric nitrate
Argentometric - correct answer-Titration of sample with standard
solution of silver nitrate (AgNO3)
- Indicator: Chromate ions (CrO4)
- End point: reddish silver chromate
, Page | 2
Mercuric Nitrate - correct answer-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 - correct answer-Sulfide,
bromide, orthophosphate (over 30 ppm), and iodide
Why does color change in water - correct answer-Presence of
decaying vegetable matter, metal ions (ie. iron) or industrial and
domestic pollution
How is color measured - correct answer-Measured using visual
comparison method
Visual comparison method - correct answer-Sample compared to
standards using matched nessler tubes
, Page | 3
- Standards prepared with solution containing cholorplatinate and
cobaltous chloride
Standard units for color - correct answer-One unit= color resulting
from 1 mg of platinum/L
2 color reporting - correct answer-True and Apparent
True color - correct answer-Color from dissolved substances,
determine using sample treated to remove turbidity
Apparent Color - correct answer-Includes dissolved and
suspended solids
Conductivity - correct answer-H2Os capability to pass electrical
flow
Conductivity of pure water - correct answer-0
, Page | 4
Units of conductivity - correct answer-micromhos/cm
Temperature conductivity should be read at - correct answer-25
degrees Celcius
How is conductivity affected - correct answer-Mobility of ions,
conductivity is dependent on viscosity
Viscosity - correct answer-A liquids ability to resist flow, higher the
viscosity the lower the flow
Relationship of temperature and viscosity - correct answer-
Inverse
Acid - correct answer-A compound which liberates hydrogen ions
and has a pH below 7.
CWEA LABORATORY ANALYST EXAM
ALL GRADES 2026 QUESTIONS AND
ANSWERS | A+ GRADED | WITH
EXPERT SOLUTIONS
Chloride - correct answer-- Major anion found in many natural
waters
- Can impart salty taste in H2O
What increases concentration of chloride in wastewater - correct
answer-Chloride in human diet and softeners flushed into sanitary
sewer system
2 most prevalent methods of measuring chloride - correct answer-
argentometric and mercuric nitrate
Argentometric - correct answer-Titration of sample with standard
solution of silver nitrate (AgNO3)
- Indicator: Chromate ions (CrO4)
- End point: reddish silver chromate
, Page | 2
Mercuric Nitrate - correct answer-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 - correct answer-Sulfide,
bromide, orthophosphate (over 30 ppm), and iodide
Why does color change in water - correct answer-Presence of
decaying vegetable matter, metal ions (ie. iron) or industrial and
domestic pollution
How is color measured - correct answer-Measured using visual
comparison method
Visual comparison method - correct answer-Sample compared to
standards using matched nessler tubes
, Page | 3
- Standards prepared with solution containing cholorplatinate and
cobaltous chloride
Standard units for color - correct answer-One unit= color resulting
from 1 mg of platinum/L
2 color reporting - correct answer-True and Apparent
True color - correct answer-Color from dissolved substances,
determine using sample treated to remove turbidity
Apparent Color - correct answer-Includes dissolved and
suspended solids
Conductivity - correct answer-H2Os capability to pass electrical
flow
Conductivity of pure water - correct answer-0
, Page | 4
Units of conductivity - correct answer-micromhos/cm
Temperature conductivity should be read at - correct answer-25
degrees Celcius
How is conductivity affected - correct answer-Mobility of ions,
conductivity is dependent on viscosity
Viscosity - correct answer-A liquids ability to resist flow, higher the
viscosity the lower the flow
Relationship of temperature and viscosity - correct answer-
Inverse
Acid - correct answer-A compound which liberates hydrogen ions
and has a pH below 7.
