CWEA LABORATORY ANALYST CERTIFICATION
EXAM SCRIPT 2026 TEST PAPER QUESTIONS
AND SOLUTIONS GRADED A+
◉ 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
- 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
◉ 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
◉ 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.
EXAM SCRIPT 2026 TEST PAPER QUESTIONS
AND SOLUTIONS GRADED A+
◉ 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
- 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
◉ 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
◉ 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.
